Proof of purchase

My Samsung Galaxy S4 was recently damaged. I took the phone into the service centre on William Nicol drive and was advised that the phone is out of warranty and that if I could bring in the proof of purchase they could apply for a warranty extension. Considering the phone is almost two years old and it had been ordered telephonically, I could not find any of the original documents and am not even sure if it was sent to me when the phone was delivered. I requested a proof of purchase from CellC who supp**** the phone on contract. They sent me a letter of confirmation with the date the contract was started as well as the IMEI number of the phone. Samsung advised that this was not good enough. I went back to CellC and they provided me with a re-print of the contract which I forwarded to Samsung. Unfortunatley the IMEI number was not on the re-print. If you look at the re-print and the confirmation letter together , it clearly is the same device . I do not understand how a letter confirming purchase that is signed by CellC and has the phone details is not acceptable as proof as they are the suppliers of the phone. I believe this is just a way to avoid paying the claim . This Sucks....