No frowning at the back please. Imre Karacs in Munich on a charm school for postal workers
"LAUGHTER is the shortest distance between people," proclaims a sign on the wall. "He who cannot smile should not open a shop," says another, ominously. All around are child-like images of happy faces drawn by adult hands, betraying a little tremble here and there.

Every morning, at eight o'clock sharp, this kindergarten fills with 12 grown-ups. They sit in a circle, gobble up the chocolate placed on their seat, and proceed to play funny games with multi-coloured scarves. In between, they listen to lectures about the ergonomics of facial muscle movement. A smile, they will be told, consumes less energy than a grimace.

We are at the Bavarian retraining centre of the Bundespost, one of the company's 12 seats of learning in Germany. At the end of last year the post office lost its monopoly, and its employees no longer enjoy the status of omnipotent state bureaucrats. Thousands of them will lose their jobs; the rest will have to learn to serve the public, rather than dictate to it. If the course works in Bavaria, there are plans to take the syllabus to deadly earnest northern Germany.

It is Thursday, the end of the four-day seminar. On their seats, under the chocolate, a paper disc awaits the pupils. Their first task is to draw a face expressing their feelings, and out come the ballpoint pens. The results show the training has not been wasted: 11 broad grins greet the lecturer. "I feel good today," they say, one after another. Giggles all around. Not a tremor of a bad vibe in the room.

They have come from all over from Bavaria, and they will do whatever it takes to excel at their jobs. Today is the last hurdle: role-play. Georg Steiner, the lecturer, sets up the situation. Stefan, who normally sits behind the counter at a small post office in the Alps, is given his orders. He is to play the "awkward customer", the one who doesn't quite know what he wants and even less how to ask for it. Ramona sits behind the make-believe counter, fully aware that every twitch of her face is being recorded on camera. Both have been serving post office customers for about 20 years.

Stefan goes through his spiel admirably, boring the socks off all present. Ramona, not privy to the plot, tries to look attentive, but loses patience after half a minute. She retreats and goes through a series of transformations. First, she looks threatened, then suspicious, and, finally, threatening. "Go away", her body language spells out .

A few minutes ago they were hugging. Now, Stefan and Ramona are screaming at each other at the top of their voices. "I felt so helpless," Ramona admits, afterwards, as she stumbles back to the comfort of the circle of chairs. Everybody is shocked, but the torture has a purpose, as Mr Steiner explains: "We put them in the shoes of the customer, and then ask them; 'How do you feel?' The answer is: 'Not very good'."

It is written on their faces. They watch the video and see themselves in Ramona's place. For 20 years they have all been sitting behind the bullet-proof glass in their own post office, responding to customers very much the same way as Ramona has just done. They used to be Beamte - civil servants - but now they must metamorphose into Fachleute - professionals who are sustained by a profound pride in their jobs. In a matter of days, their post office is to become open-plan, the glass shield will be taken away and the new orders are that the customer will henceforth be king. This is pretty revolutionary stuff anywhere in the German service industry, let alone the public sector.

And so they amble in front of the camera, enacting the mundane encounters at the post office, but this time with a novel plot. Everything is just wunderbar, eye contact and even the curvature of the lips is immaculate. But old reflexes still creep in. "What was wrong with that?" asks Mr Steiner, analysing the video of the last situation comedy. No one knows. "You told the 'customer' to come back at 11 tomorrow," he explains, slowly. "Surely it's up to him to make an appointment with you at his convenience." "Oh, yes," they chant in unison. "The customer is king."

There is one final test before the 11 graduates are ready for the real world. Mr Steiner decides to lead from the front. He poses as a customer who has been notified of a registered letter. He has the slip, but no identity card. His trainee is unyielding: no ID, no letter. "You agree you know me," Mr Steiner says. "I come here three times a week. Every time, you say 'Gruss Gott, Herr Steiner.' So can I have my letter, please?" It sounds reasonable. "I am sorry, I can't do it," his female pupil repeats hypnotically, on the verge of tears. Everybody seems devastated by her failure.

But Mr Steiner, reverting to his true persona, approves. It might seem inhuman, even silly, but this particular display of bureaucratic obstinacy can be explained as a market-friendly gesture. "The customer posting that registered letter has paid you to check the ID of the recipient," Mr Steiner rationalises. "Just don't say that you're only following the rules. That really irritates people."