MTN - One sided change of terms

I have been a MTN customer for the better part of 15 years. In 2016 I was about 4 years into a contract and a gentleman from MTN contacted me and begged me to upgrade which I eventually did after he explained all the added benefits I would receive, which included: - 350 min anytime voice calls -1 gb date (+ 1gb promotional data) 500 free sms's

At some stage the promotional data was removed, which I did not complain about because I did to use so much data. Then I noticed at the end of 2019 that I got a message to say that I am incurring additional costs when I was sending a sms. It transpired that the sms benefit was removed. Again I did not complain as I send, at most 5 sms's per month. On the 17/12/2020 I noticed that I was not allocated my usual 1024 mb data fot the month. As I was on holiday I bought aa gb data for R149. I also called MTN and the lady said I do not get data on my contract. Huh? I wrote an email to complaints@mtn and although the say they tipically respond within 24 hours it has now been nearly 3 weeks without a response. I called MTN on 4 separate occasions and spoke to 4 separate consultants, and the last one (Mrs Khumalo) today informed me that the reason I no longer receive the data is because I am now over my contract period and the remove all the ancillary benefits (ie data and sms's) , although my monthly premiums stay the same. This is nothing less than theft and ******ion to force clients to upgrade. I wish for MTN to confirm if this is correct, and if so I would take the matter to the ombud and move my business to another provider.