Extremely bad service from MTN

I have experienced such bad service from MTN that I don't have words to described it. I asked for a change to my plan. A change was made but not as per what I was told and promised. A year later after many visits to the shop and emails and no resolution although they are deducting more money than what was agreed. The can't even fix the issue I have of not being able to view my statements and invoices.