Defective Device

Purchased a Sony M4 Aqua through FNB smart devices. Ever since I received the device IV been having a problem and I've only had it for three months. The battery doesn't last, the phone overheats, storage is incorrectly advertised. Contacted FNB who put me in touch with Sony. The only way they are willing to look at the device is if I take it in to the branch. I'm in midrand and would need to drive to Benoni... This is pathetic and I'm highly disappointed. I can't believe this and the lack of willingness to assist...