MTN Shocking Service

I have been trying to cancel my LTE line with them. I phoned the 135 number and tried to speak to retentions. When I finally got through, they told me that I had to go to a store. I went to MTN Bluff store. They initially said that they couldn't help me and I had to phone 135. Then they finally figured that they could log a cancellation. They said that I would be contacted by retentions. It never happened. About a month later, I got an email saying that they were glad that I had changed my mind and didn't want to cancel. I went onto the website and immediately logged a query stating that I did want to cancel. This morning I phoned 135 and got a "Service Champion" who took all the details and then put me through to ??? - the phone is still playing its loud repetitive noise 20 minutes later!!! How is one supposed to deal with this company???