Incorrect charges on my account

I purchased a router a month back. My installment is R129 per month for a 5gb. Today i received a sms that states im owing R129. I would like to know how is that possible. I even requested the sales consultant to make the limit only 5gb i dont want any additional charges on my account. The sales consultant assured me once i have reached the 5gb no additional fees will be charged cause it will a on a top up basis where i can purchase on my own.

This is very unprofessional. I cant be paying r703 just for having my contract for a month.

I am extremely not happy about this.

Please can someone assist me and rectify this error.

First time im purchasing something from telkom and it will definitely be my last