Wrong details are going to cost me a bunch!

Ever since I have done a sim swap with Telkom last month, I have not been receiving accurate details about my remaining data balances. I enquired about sms I have been getting telling me that I am surfing out if bundle while when I check my balance, it says I have more than 2gb left. The contact centre assured me the balance detail is correct when I contacted their online chat operator. Yesterday the balance shows more than 2gb left and they blocked my line yesterday and will be charging me an unbilled usage of R500 on top of my R199 contract because of their balances not refreshing correctly on the websites and the apps. How fair is this that I will have to pay for a mistake on their side which is out of the consumers control. I told them I am on holiday and won't be reachable on voice line the whole time and would appreciate mail as main form of communication but still have received no further mails than them asking my current contact number....is this acceptable or is this the standard we are getting used to and just paying up without a fight? UNACCEPTABLE! If this does not get resolved I will be taking it further to Consumer Protection Act!