Billing issue

I have been trying to get through to MTN for the past couple of weeks, for the first time today I called and eventually someone answered but guess what line disconnected before I could even get some assistance. My account was debited this past month but it was a bit more than usual could someone get back to me with regards to this. I am so tired of calling and not getting any assistance. This happened previously and I was told that the discount was not processed for my contract so if this is the case please rectify.