Customer definitely comes last every time

I have a data SIM and have been informed by Cell C I cannot make or receive calls nor SMS because it has not been activated to use airtime. Because of all the prior problems (not being able to check balance from the modem, not being able to load bundles concurrently as the older bundle is not depleted only the latest one) I put R.1,650 on the SIM and waited for the after midnight data to deplete before loading another bundle so I don't lose data. I checked my balance and was informed I have over 36 GB after midnight data and R.1,650 on 8th July 2024. I struggled to use up the data and when it was finally depleted 10th August 2024 I went to convert the airtime to data there was none. I'm told that the airtime was used out of bundle which is a contradiction of what I was informed of prior, that airtime could not be used on a data SIM. Also, the agent claimed my after hours data was depleted on 7th July which I can conclusively prove with the screenshot I took (because these problems are ongoing) was not the case. She then changed her mind and claimed on the 4th August I had over 12 GB which sounds about right. If I consume 1.5 GB per night the data should run out on the 10th, so where is the R.1,650 of airtime??? I have previously lost 60 GB and 40 GB, contacted customer service and been told I was correct and would be contacted via email as I do not have a cellphone (I wish to do as little business with these companies as possible) but never received an email. I was informed on the latest phone call that an option was entered to prevent out of bundle usage on this SIM but that was always the case, why did the system reset the option? I was asked for a case number but surely the manager and agent should know Cell C do not issue case numbers - I certainly did not receive a case number for this or any other prior complaint. The best is I can get a name (Lindy in this case) but it never seems to make any difference. All these errors are the fault of Cell C but the customer always pays. No point calling and having to repeat yourself OVER AND OVER to someone who cannot/will not understand!