NO call back... over charged

I was un knowingly moved from Nashua mobile to vodacom with my contract. this month i was billed R2600 rand for out of usage costs. however, i had a block on the limit of usage. these ametuers had me pay and hold to speak to customer ervices for over a hour with no answer twice. eventually, i went to one of the branches in N1 city. the consultant wasnt even able to get through. i raised the query with him and he said \nashua mobile was suposed to inform them of the block". now how on earth is that my fault if they do not do what they are supposed to. so the consultant told me to go and reverse the charge at the bank... which ofcourse i am not going to do because they will blacklist me. i then said that i wnt to be called back that same day as i had already spent a hour and a half in thier offices. it has been more than 24 hour and still no call. i have now been waiting on the line for almost 20 min again while typing this. i still can not believe that they would charge me and send no sms what soever to inform that the out of bundle usage has started..."""