Unauthorised charges - unfailry treated

I have contract of 350 top up and have my top-up on the 12th of each month. I noticed for the past two months that I was running out of air time. I went to the Randburg Square branch to ask why it was the case. The assistant took my phone and did something, after which he told me he had removed whatever I was being charged for and that my phone should be fine. At that stage, I bought airtime for a R100, which I used until my next top up on the 12th of July, at which time I still had about R37 airtime, which then added to R380.00. I noticed the airtime was still reducing by huge amounts. Between the 12th and the 24th I had only a balance of R27.00. By then I had gone to MTN 3 times already. I went to complain 5times. When I spoke to the call centre, Busisiwe, she tried to give me another number and accused me of having app**** for MTNloaded. I told her I did not and she rudely dropped the phone in my ear. My phone is now on zero airtime. I want the MTN loaded to be removed, my phone settings of Data Sense Restrict background data to e enabled and my airtime refunded. Ref received was ***.