Impossible to resolve account issues

How does one resolve an issue with your account?????

I received 2GB free data every month for my contract over the past 2 years. My May 2019 invoice is incorrect on the amount being deducted for this service and I attempted to contact Cell C to resolve the issue...

After 2 days of failing to contact them on every support number available (when going through multiple automated menus you get a RICA message and the call returns to the main menu). I then submitted an online query through their website. A week later, with no response on the web query, I eventually got to speak to a consultant by going through the new business (Sales) route on their support numbers.

They gave me a reference number and said they will resolve the issue and get back to me. A week later, with no response, I sent an email to their customer service mail, ********** It is now another week later, with the invoice due for payment, and still no response from Cell C...

This is the worst customer service I have ever experienced. I have been with Cell C for almost 15 years, but this will be me last contract with them if they cannot resolve this issue, and if they cant fix their customer support call center.