Fed up

I did an upgrade in April 2017 at Vodacare Vanderbijlpark,and since then I have been struggling with the account. Zelda did the upgrade on the wrong package and had to do an upgrade reversal and process it again, the line has been suspended a few times the invoice every month since then is R70 more than what I signed for and no one is fixing it or even giving me answers, Zelda says it's not her problem even though she was the one that processed the upgrade on the worng package in the first place. Now the line is suspended again I am not going to pay more than what I signed for and have been struggeling for 4 months now and can't seem to get any help or answers. Never have I had any problems like this before with any of my accounts. This needs to be sorted asap for it is not my fault.