Incorrect billing/statement

HelloPeter has turned out to be MTN call centre now because all the queries that I've logged with MTN call centre were successfuly resolved after I wrote a report on HelloPeter. For a big company like MTN that is disappointing. They sent me an incorrect statement. a statement which includes an invoice which I paid in May already and I literally did a reconciliation for them dating back March 2015 for them to actually understand that the statement is incorrect. They were still unable to resolve my query following all my effortt of performing a reconciliation (something that a big company like MTN should be capable of doing). The call centre lady who was surprisingly very friendly could only take note of my query and gave me a reference number for my call ***.