Daily Telegraph readers' offer

[abstibus]

I bought some DVDs with a free CD from a Readers' offer in the DT. They arrived on time, but there was no receipt for payment. I had bought them to give as gifts from my department to some colleagues overseas, and under the rules, I can claim using the petty cash system , as they cost just under thity pounds. I have written to the company explaining that I need a receipt but have had no response. The company is called DUET, at 32 Tudor Road, Lincoln, LN6 3LL. There is no phone number and I canot find a web address. How should I proceed? Has the DT, which published the advert, have any responsibility in this matter, or does anyone have any advice for me? Many thanks.