Paying for sim contract I never asked for

Made an upgrade on one of my contracts, it was a special of 2x huawei P40, received my parcel, with the package I found two simcards which I didn't use them. But when I found that one of those simcards is added to my contract at a R65 charge per month I phoned and told them I don't need an extra contract simcard, as I am already having 3 contract numbers with them, and this was done without my concern, I never asked for another contract sim because I hardly use them. They promised to sort it out, I've been given different ref numbers and the problem isn't sorted. I'm paying for a sim that I don't use, please help because I reported this within a week after I've upgraded now its months and they ain't sorting it out, because I told them to cancel the number I don't need it.