Contract frustration query

I had a contract with telkom for WIFI deal for R149 per month account no: ********** 80.I have made EFT payments from June 2017 till february 2019 totalling R4098.00 ref used for EFT: ********** ********** 85030 but now im surprised that I have been handed over to VVM attorney with a balance of R3352.64 ref: ********** 86.I have email them proof of payments and logged a complaint last year ref: ********** 90 & ********** 95 to query my billing on my account that is too high for a contract of R149pm for 24 months the total repayment was suppose to be R3576.00 so with payments made plus the vvm balance total contract BALANCE R7674.00 how is that possible ?When i go to the maponya branch they are always offline and referring me to billing department which i have logged complaints but nothing was changed.