phone damaged

I bought a t3 Sony phone using my Edgar's account used the phone 4 4moths afterwards had a problem with the sim reader took it to the rosebank branch n ws told to go to edgars dey not accepting phone. Edgars took it in for repairs and the report from mtn repairs comes back stating that due ro my negligence im responsable for the damage and have to pay R300 to get the none working phone back its their service fee.its has been a month without the phone that im paying its installement and now im left with no fone but still paying for it. I juts feel its unfair to be sold phone that are likely to damage within the warrenty period and be put on the blame with their negligence forcing you to agree to the damage and keep paying for the phone you dont posses,hope this matter can be resolved. Its not a nice feeling that with the little u hav to get yourself something and someone like the store robs u off it. Its sad....even with the fact that getting a phone from CNA is not a wise choice cause taking it in for repairs all fault its hustle,you are told only 1 brach does which is the glen,means u have travelled from wherever u are to the glen mall other don't comply,that's cna for you.