Rude and bad service

I took my faulty hand set to MTN CarletonCentre in February and I got assisted by a lady called Ivy. She was reluctant to take my faulty hand set because if was not purchased as the shop but order direct from MTN and delivered to my work place. Within the first month the phone did not want to switch on and MTN advised me to send it to the nearest store which I did. Ivy took my phone and gave me her numbers to phone the next day just to check if MTN would accept my faulty hand set. I phoned her the next day she confirmed that it was taken in for repairs and it takes long. I called her again in March just to follow up and she confirmed that it was not with her. I phoned today and she was very rude saying I should phone her in the afternoon as she is currently busy. I asked her why can't she phone me when she is done with her work because there is a number that she was supposed to give me so I can do follow up with repairs center. She told me she had lots of emails and the number is somewhere in between her lots of emails. She confirmed that it is my responsibility to follow up with her as I am not her customer. I told her I was MTN customer and I am supposed to be treated