I am now also having phone calls and letters from the PRS. I rang the MVRA the other day and the bloke said "it must be somebody winding you up mate" I explained about all your comments and several other local businesses having calls and he finally agreed to put me through to the free legal helpline. A solicitor rang me back and said "yes, you should have a license" When I asked about section 72 of the copyright, designs and patent act 1988 he had not got a bleeding idea and I apparently knew more about it than he did.
Basically, if the customer does not pay for admission to your premises then no infringement has occurred, BUT if you charge for goods or services then the customers is treated as having paid an admission, BUT only if the prices of the goods or services are SUBSTANTIALLY ATTRIBUTABLE to the facilities afforded for seeing or hearing the broadcast or programme OR the prices are exceeding those that are usually charged there AND which are partly attributable to those facilities afforded for seeing or hearing the broadcast.

My way of reading this is we can tell them to get stuffed as the customer does not pay for entry to my premises and none of my charges are attributable to my music system.

Graham