Can someone please help me?

I had a contract with Nashua Mobile who has since closed its doors. My contract was taken over by Vodacom. My Samsung phone broke last week and Samsung will fix my phone free of charge but they want proof of purchase. Since I had not purchased the phone but gotten it on contract Samsung wants a copy of my contract. I have requested a copy but Vodacom says they don't have it. So now my phone can not be fixed by Samsung. Surely Vodacom can give me a letter so give Samsung to prove that I have a contract with them and the handset in question is part of that contract?