Erroneous billing from Vodacom

Dear Vodacom, I recently received a call notifying me that my account is in arrears for R700, this is really confusing me as i have been paying on monthly basis and will affect my credit profile. I have been with Vodacom for more than 20 years now. Now you leaving me with no choice but to look for a different service provider. Would you please rectify your mistakes as soon as possible. My Number is ********** 461 and i am Mbengeni Godlip Sitholimela. Now i cannot get credit from stores due to your erronous statements, this is happening for the second time