These calls usually kick in at around 7pm when your tolerance level is just above zero. You know it's double-glazing, fitted kitchens or BT telling you how cheap it is to ring your granny in Greenland, because they can't pronounce your surname. And if you're a woman, you must be a "Mrs".
Direct selling is all about persistence. You've said no to basic double- glazing, a uPVC front door and a conservatory. Just when you think you're off the hook, they play their trump card: "How about your soffits?"
For research purposes, I prolonged a recent call. The double-glazing company informed me that they would send "a fully-qualified surveyor to inspect my property". But why, I asked, would a qualified surveyor be selling double-glazing? Within seconds, the "supervisor" had grabbed the phone. Did I want to take advantage of a promotional offer of 40 per cent off the "usual" price if I booked an appointment there and then, or would I prefer another quote (full price, of course) that was valid for a year?
Joanne Scott, from west London, agreed to a visit from a sales rep to give her a quote for a conservatory and double-glazing. "He was so persuasive," says Joanne, who usually prides herself on being blunt when it comes to fielding sales patter. "I wasn't happy, but we found ourselves signing just to get rid of him." She cancelled the order the next day and stopped the deposit cheque.
The Consumer Protection Regulations 1987 provides a seven-day cooling- off period during which you can cancel a contract made as a result of an unsolicited visit by a salesman to your home, including appointments made after unrequested telephone calls or leaflets, and demand the return of any deposit paid. If, however, you initiated the salesman's visit, you are not covered by the regulations.
Rows and rows of uPVC windows and doors in every permutation testify to successful sales pitches. And there's still plenty of virgin territory out there, where double-glazing companies are battling to get their foot in the door.
Direct marketing is hugely successful and generally reputable. According to Martin Bartle, of the Direct Marketing Association (DMA), it's a pounds 7bn industry in Britain, covering everything from mail shots to telesales. Surely telemarketing is most unwelcome? "It's the most intrusive," says Mr Bartle. "But just because it tends to be double-glazing, it's not to say that the company isn't competent or reputable."
The DMA's 700 members cover around 70 per cent of telemarketing providers. "Our members' relationship with the customer is of the highest importance and we're here to raise the standards of our industry," states Mr Bartle. Members must obey a stringent code of practice, giving their name and company when telephoning, and offering to call back at a more convenient moment. Disreputable companies will refuse to do this.
By calling the Direct Marketing Helpline, individuals can register that they wish to reduce unwanted telephone sales calls, mailings and faxes they receive at home. In turn, members are bound by their code of practice to make a check against the register before cold calling. It is likely that a new piece of legislation will be passed this October, making the use of a telephone preference list compulsory.
But we may well be a fickle bunch. According to Mr Bartle, most people decide not to register once they know what they'll be screening out. "The majority of direct marketing is creative, appropriate and well received," he comments.
Della Howell responded to a leaflet through her letterbox, offering a discount on double-glazing if she would agree to her house appearing in promotional literature and advertising the company on a board outside for four weeks. "The quote was only slightly less than the others I'd had," says Della. "But I thought they'd do a better job if the work was going to be photographed."
To her knowledge, the company never took photographs and the advertising board was stuck to the plaster on the front of her house for eight weeks. "I kept ringing them to take it down. Eventually it fell off, leaving four unsightly marks." She failed to get the company to repair the damage. "I was so fed up, I gave up," she says.
One former kitchen salesperson, who asks to remain anonymous, confirms that there's no such thing as a free offer. "Every 'free' hob, oven or extractor fan is built into the price." Offering a discount for a "show" kitchen to clinch a deal was part of the process. "You'd say you were ringing your manager to see if it was possible, when in fact you were talking to their answering machine."
He often found he had to think on his feet to get a sale: "As I finished my sales patter, one client thanked me but said she'd already decided on a Smallbone kitchen. I'd just been reading somewhere about the relationship between the worker and the workplace, so I asked her if they were sending an ergonomist to see her. I then spent a couple of hours measuring her in 45 different positions in the kitchen, while her husband sat there sniggering. It was pure snobbery that made her buy my kitchen."
We'd all like to think we wouldn't be taken in by such blatant flattery, and certainly we should all be more aware of our rights since the advent of TV and radio consumer programmes. But there's a flip side to every story.
One kitchen sales company used a pseudonym for customers during training. A nervous new recruit making the inevitable phone call to "head office" from her first clients' living-room, suddenly realised she'd just referred to them as Mr and Mrs Raving Bonkers.
Direct Marketing Helpline: 0345 034599