cellhone faulty sony m4 aqua contract

I took a contract on 2015/08/03 the phone worked well for the first couple a months. I there after kept going back yo the telkom store in Chatsworth complaining of poor reception. After a couple of months to and from thr supplier i requested that they book in device february 2016. I got cellphone back on 2016 03 11 and today 2016 03 14 I find myself having to book in the same phone just 3 days later for the same fault. If a product is faulty should not the consumer be warned. I know that i did not breach my contract in any way as my account is paid up. I also went to the extent of getting a linked number and a new device just to be able to continue using my contract. Its time that Telkom either give me a replacement device or if they cannot then cancelled contract or charge me a contract price in relation to me using my own device. My contract number is ***