cell C poor customer service

the Cell C call center had contracted me to upgrade my contract , i have taken a contract where the rate promised contract value less than my original, i have since received statements deducting more than the actually contract value, have have exceed any of my limits yet the are deducting extra from me.

i have tried the cell c customer support line but they do not answer, the cell c stores say they cannot help me and refer me to the call center. Why is it that Cell C have agents working when they have to gain a new contract but never assist clients when they require help. i am now paying more than my original contract , this is the type of service you get from cell c.