Incorrect billing

I’ve been with Telkom for the past two years and I never miss even one instalment in my data contract and to my surprised last month I got an email with my statement billed 1198 and my data is 269 a month I went to a Telkom store, they are don’t know what is 1198 for and they advise me to call the billing department and I did and she told me it’s the subscription that is added, its system error. I asked them to remove it and she told me she is escalating the matter so that they do investigation but till today it’s the same story…the 1198 is still due and my question is who is going to pay that amount because I’m not paying for something that I don’t know.. I’ve been calling them for more than 10 times and nothing is happening… I’m so disgusted because this thing is going to mess my credit score..**** service and unprofessional staff members