The two customers said they received minor injuries after pads used to heat the neck pillows overheated.
A further three customers have complained that the pads began smoking when they used them. M&S said it was urging customers to return all the items to their nearest store for a full refund.
Although no complaints have been received about the back pillow, which went on sale in August, they are also being recalled as a precautionary measure.
Some 4,200 neck pillows have been sold since they went on sale in M&S stores a year ago.Reuse content