incorrect billing

Telkom has been over billing my account with R500 more for the past four month, i called to find out why i was told i went over my spend limit, when questioned how because my limit is 0.00 which means i can't go above what they provide and it has always been that way for the past 20 months, then said i bought data worth of R500 on my data sim when i asked how because that is a closed line i cant top up on it they said they will escalate to billing, held on for 40 mins and i was told the system has issued but the query will be logged and i will receive a case no.. few days later when i called no case was logged, a new case was logged on the 21/04/23 and i was supposed to receive feedback within 72 hours Wich i didn't, and when i called i was told the case was allocated, called again 7 days later the case is closed because the was "insufficient information" which they couldn't tell what..asked for another escalation of which i am still awaiting a case number for and that could only mean it was not done.. i spent over mins on the call and still did not get any help.. i am owed 2k and they are giving me a run around..i am very frustrated at this point