Harrassed by VODACOM for 2015 contract in 2021!

I have repeatedly been receiving letters for 2015 contract that was cancelled in 2017 for an overdue amount of R170.15. The letter started this year 2021, THIS MAKES NO SENSE AT ALL. After being sent from pillar to post, being asked to speak to different departments *** then 082135 then ***, I have had no joy at all in having my problenm resolved. Vodacom has contacted me after 4 years to pay this amount, claiming I have not cancelled my contract. Pure frustration and many tears later I decided to pay the amount on 25 August, and was given an email address ***. Today 27 Aug 2021, I called *** o cancel the contract and was told I answered the incorrect security questions so they could not help me. HOW WILL I REMEMBER QUESTIONS FROM 2017, when I have since relocated to another province.....I cannot express the frustration that I feel right now. I am shedding tears as a result. I WILL NEVER EVER DO BUSINESS WITH VODACOM FOR AS LONG AS I LIVE. When I do get calls from then its from a *** number which shows "Potential *****" Does anyone care anymore in S.A that there are people being De*****ed, DOES VODACOM CARE?