Incorrect billing, charging me for a extra account

I have four dstv staff accounts, in july they charged me for 3 dstv accounts so i personally went to pay in the extra account even though it was not my fault, so that there won't be any issues. Then in August they charge me money for 5 accounts instead of 4, i phoned numerous times to get this fixed. Today i get told i must send a bank statement to show they over charged me, can't you guys fix your systems omg! why is it so hard to correct a simple problem. Complete incompetence I tell you. if you knew your systems were going to cause this much problems why not put extra staff in to answer calls or change your billing system so that you can handle the load. Why must i send you proof of you charging me for 5 accounts when you should be able to see it on your system fix your problems, only reason im with you is for sport