missing money

Three men go into a television shop to buy a television, they pay £30.00 for the t.v. . Each man gives the salesman £10.00 each, and leave the shop with the t.v. But the manager of the shop tells the salesman the t.v. should have been £25.00 and he must go after the men and refund the £5.00. So the salesman thinks he can make some money out of this and gives each of the men £1.00 each back and puts £2.00 into his pocket. So each man has paid £9.00 .
Three times £9.00 is £27.00 plus £2.00 the salesman put in his pocket is £29.00 , Where did the other £1.00 go ???????