the cellphone has been on repair from 07/09/2015 still no response

I bought a cellphone at Edgars few days later the phone refused to switch on... I took it back for repair on the 07/09/2015 was helped by a lady called mamello she promised to call me back and give me a feedback about the phone which she never did....I went to the shop an enquire about my phone she made an excuse that the phone is not working but she will call mtn and find out....again in December I went to the store to find out still my cellphone is not back from repair and the consultant is still not in contact with me...we now on the 5th month since my phone is on repair ....while when an enquire I get a very bad attitude from mmamelo....not a happy customer