***** on airtime

I have always been receiving promotional sms from cell c for the past 7+ years. On 25/12/2017 I was charged for these promotional sms when I called the consultant told me that I opted in for promotional sms on 24/12/2017 which I never did. She then sent me 2 sms that I must use to opt out. I followed the instruction but the response was unsuccessful and I'm still receiving more promotional sms.

1)I want proof that shows I opted in for promotional sms on 24/12/2017 or MY MONEY BACK please. 2) In future please do not send me any promotional sms.