I guess this the only platform I can use to be heard

I took up a 24 months with Cell C which expired on the 16th of May, called in February to let them know that I will not be upgrading for that particular contract, I was advised that my last payment will be on the 25th May. I called in again on the 3rd May to check if my request was processed successfully, only to be told that it will not be cancelled on the 3rd June instead of the 16th May, cause I need to put a 30 days notice. I will not accept such nonsense, I took up 24 moth contract till 16th May. Spoke to a supervisor who I am still waiting for feedback from, a month later no feedback. Benefits were loaded today, which are not due to me as contract has ended on the 16th May. I WANT THIS CONTRACT TO BE CANCELLED IMMEDIATELY BEFORE I CANCEL THE OTHER 2 CONTRACTS