copy of purchase

I took a contract with telkom mobile in 2013. I got a Samsung S4. Now the phone crashed. I took it in at Samsung and they told me that their warranty takes 24. My contract is 18 months. They requested I get proof of purchase from my dealer. Called the call centre they refer me to the branch I took the phone from, which is Fourways. Went to Westgate they dont have a copy the only place they would have this is fourways. Sent an email to the branch manager and he only sends me an invoice I have. What I need is a copy of purchase that proves when I got the phone and that shows the IMEI number. Can I please have this because it is a document that is going to prevent me paying over R2500. I keep getting we dont keep it in the shop we take it to head office. Surely there is a way of requesting this. The contract is in the number ***