Help with business to business dispute?

Hi, My business was supplied with a faulty product in december 2010, we found the fault more or less immediate and reported it over the phone. there Representative came out to have a look at the damage so they are aware (agree?) well they still have done nothing to sort it so I have written a letter to them telling them I have had enough of waiting and want them to collect and refund me the money I paid as I have waited long enough! There reply to this was that they was not aware of an issue (what Rubbish) as they have nothing in writing and supplied me with their terms which state all faults must be advised in writing within 5 days of delivery. I must have imagined their representative inspecting the fault and all the conversations since!! This representative is self employed so they are not his boss but I still think he would be reluctant to defend us if it went to court as he would not like to upset the supplier. What I really want to know is do I have a legal argument to get my money back? p.s another company we deal with reported the same fault with the same product only a few weeks before us (if that has any baring)