Cellphone contract misinformation

I renewed my contract this year with mtn because I had lost my phone, I was told that the new contract was going to deduct R150 for two months but it never happened they deducted more and when I asked about apparently it was the "system issue", the answer I got from both the branch(vryburg) and Helpline. I asked my package to be 200mins with no data because I have wi-fi at home (it was an option that I was given and I chose it), they still load 100mins with data every month till now, okay shap, now that I made peace with 100mins all network, they change it to mtn to mtn only. When I call and ask they tell me to go back to the branch. I think the only time I go there is when I go cancel the contract with Mtn, it's too much now, the only they do is to blame the system.