Well unfortunately the letter to HQ produced a very weird response! I received an explanation of what had gone wrong (aka "the accident"). I was informed that the error had been rectified ... and I was told that a 3rd pair of jeans would be delivered to me "free of charge" as a "gesture of goodwill". Naturally I was delighted. Until I received an invoice for £20.99 ... the price of the "free" jeans plus a p&p charge!

OK, will do. Thanks very much citizenB.

Here’s a bizarre situation! I received a ‘Marisota’ catalogue which included an order form. There were two offers printed on the form ... “a free weekend bag” and, more importantly, “20% off your first order”. I decided to order two pairs of jeans @ £16 each. Because I had no intention of entering into a credit agreement with this mail order company, I enclosed a cheque (payment in full) with my order form, and sent them off in the envelope provided ... this was on the 3rd June 2013. The cheque amount was for £29.59. This sum was calculated as follows: Price of jeans = £32, but with 20% (-£6.40) deducted as it was my 1st order = £25.60; plus post and packing @ £ 3.99; TOTAL = £29.59 My bank statement shows that the cheque for £29.59 was cashed on the 10th June 2013. The two pairs of jeans duly arrived ... but there was no sign of the “free weekend bag”, so I contacted ‘Marisota’ (aka JD Williams) via email to ask where it was. The reply I received was evasive, so I ‘phoned their customer service department to complain. The member of staff I spoke to arranged for a bag to be despatched to me, and I received it within a few days. Naturally I assumed that was the end of the matter ... I’d paid for the items; I'd received the items; and I'd received the free gift. However, a month later (11th July 2013) I received an email informing me that I owed £34.99. I immediately ‘phoned the ‘customer service’ department and explained that I didn’t owe anything at all ... and in fact I had never owed them £34.99. The person I spoke to said that there had been “an accident” with my account. She assured me that “the accident” would be remedied. I asked for written confirmation that my account was clear. She was reluctant to provide written confirmation, but she said that the next ‘account statement’ that I received would show that there was no outstanding balance. Annoyingly I received the ‘account statement’ this morning which indicates that I still allegedly owe £34.99! So I now have the hassle of trying to sort this out ... but in the meantime please could anyone tell me whether there are any relevant Laws, Acts etc that I could cite in my communications with Marisota/JD Williams, which might add more ‘weight’ to them?