Breach of contract on a SONY M2

I bought sony M2 on the 6/11/2014 from MTN store at South Gate mall. On the 3/01/2014 it stopped charging, and i took it back to the store on the 19/01/2014. I got assistance from Themba, who did an inspection on my phone to check for any damages before taking it in. He confirmed via signing a checklist form that there were no physical damages (scratches, cracks, attempt of fidgeting), and i also signed the same. I left my phone at the store and he advised to come back within 3-4 weeks.<br> To my surprise when I went back on the WE 14/02, Themba told me that my phone was returned from the repair centre without it being repaired because they claim that the phone had been opened at the back. Themba and I went back to the MTN repair centre in Midrand on WE 28th February. (he could not understand why the repair centre claimed that there was fidgeting on the phone when he confirmed that it wasn't when i checked it in).<br> At the repair centre we were told (by an Indian Man) that when they received my phone it was opened at the back, and it didn't look like any other `sony M2's. And their final say was that they will not repair it for those reasons. Till this day i haven't gotten help!