MTN offers which could cost you more than offered

Shortly after upgrading my MTN contract for the 5th time in May 2020 I was contacted by MTN's migration department on the 23rd September 2020 at around 15:44 Reference for the call was N*** where they had offered me extra data and minutes for free, in December I all of a sudden received a bill for R1488.67 from my usual monthly bill of R1049. I first thought I was an error from MTN and that it would be corrected in January but than I was debited R1199 and I couldn't understand why. This went on in February and March. On the 20th April I sent an email to Customer care informing them that if they do not cantact me I will cancel my debit order, I later on called them at 09:45 Reference for the call is *** and explained my situation the first lady told me that the reason for the increase was because of the VAT percentage increase to 15%, I asked her if she had been smoking something as VAT went up in April 2018. I than told her to call her supervisor, a lady by the name of Nerisha who was the team leader spoke to me and told me that she would escalate it to the retentions department. Nothing happened as the 25th came and again I was debited R1149. In May 2021 I cancelled my debit order as no one from MTN contacted me to rectify the problem. In June I sent a follow up email to follow up, still no response. on the 29th of June I got a response from MTN saying once again that they were going to escalate the matter to the retensions department. on the 1st July I responsed by saying that this is unacceptable customer service and that I could not understand how can a matter take 2 months to get escalated to a department and nothing happens. on the 19th July I sent another follow up email, I received no response. on the 2nd August I contacted the migrations department reference nr for the call was *** the lady’s name was KHanyisile , she informed me that she is going to contact a person at the migrations department to correct this(see if they can cancel the switch in my package and go back to the old package). At 17:31 a lady by the name of Palesa emailed me and asked if she could call me(not sure why didn't she just call) I responded the next morning and said yes she can. She never did, I sent a mail on the 5th asking if she is still planning to call. I got a response on the 6th saying this "Good day Jody, Thank you for your email. Kindly be advised that the below has been escalated to the retentions/cancellations department and they will contact you for feedback. You may also call 135 from an MTN sim or 083135 from a landline or non MTN sim and select "Option 3" from the voice menu to be transferred to the cancellations department or email: ***. They are available on Mondays to Fridays between 08h00 and 17h00. We look forward to being of service to you in future" I emailed the retentions department on the 10th August got no response. I emailed the retentions department again on the 30th got no response and again on the 31st still got no response