Very bad service-no answer for 40min daily?

Goodday my cellphone Contract which I entered into with MTN grand central C T, has expired, in Oct 20. I hve since made an enquiry with the said branch as well as MTN, Kenilworth Centre, regarding cancelling the contract. However I was requested to call there retention service number, 135, of which I tried calling since, last week Tuesday the 15/12/20, of which I've been holding on for 40min on end with a voice recording online and no answer or assistance at all. I had also in the interim called and enquired if a manager or supervisor can assist and once again was asked to call the number 135.

Imagine a huge cellphone enterprise, that gives there clients such poor service and let alone, no contact at all when calling in to cancel my cellphone Contract. MTN you suck your service is extremely poor, please get awake up.

Regards Waheba. Jakoet ***