Thanks again for replies, so my best bet would be to write that letter, send it recorded and not ignore them? Also @scarletpimpernel yes the item that was "stolen" was recovered. Also what response would I likely get back off them?

thanks for reply.

Hi people Last week I was shopping in Asda when by accident I failed to pay for 1 item, so as I walking out of the store I got called back in by a security guard who took me into a back room and said I stolen this item which I didn't. So he made me sign a form with my name and address to say I am barred from every Asda in the UK or he would ring the police if I didn't comply. So then he let me go and I thought that was the end of it, then today I got a letter off "drydensfairfax solicitors" and here is what they said: Dear Sir, Our client Asda Stores Ltd has instructed us to contact you following an incident at one of their stores on 28th November 2012. As a result of that incident our client has suffered a loss that they are entitled to recover from you. The amount due is £33.50 resulting from Staff and management time to detain you, observe and apprehend, preparing evidence, writing reports and/or liason with the police. Then they add: What will happen if you don't pay? Asda stores Ltd have asked that we obtain payment of the full amount of loss they have incurred. As a firm of lawyers there are a number of steps that we can use to secure this payment off you. Act now to avoid any further action taken. So can someone give me any advice on what to do? when I get a new letter off them should I just write "not known at this address" and return it? Or do they have more powers like getting the police to come knocking considering Asda is a large company? Thanks I would appreciate it. Gary.