MTN WIFI Router

I ordered a WIFI router and it was delivered. I was happy with it. Then after 3 weeks, the third router was delivered. I called to reported their error and that I do not need the second one, I was advised to take it back to the nearest MTN branch. I did that on 4 November. When I called they confirmed that it was cancelled. But I'm noticing that my bill is bigger than the one we agreed on, when I call they asked to call International Call group. This international group does not take my calls nor respond to my emails. My internet services has been cancelled because I refused to pay for the 2 routers.