Sony phone is the worst fine ever

I purchased a phone from telkom Sony Xperia. I am having endless problems with the phone. My husband and I took the same contract with the same phone, it freez a lot, software is terrible cos the phone just does its own thing. We paying R350 each for the contract and we having problems with this phone and we have to keep factory reseting the phone... A month ago I just received my phone from telkom after it went for repairs it came back with the same problem the camera just stops working. I just need Sony to replace my phone or it's gona get a lot intense.