I got ****med by MTN

Good day I got ****med by MTN i went into shop for the 70gb month to month plan for R290 it was activated with instalment fee obviously and 3 days later I get a call from mtn, - they now want to offer it to me for cheaper - only R260 I told him I just got an upgrade I’m good, he carries on. I tell him I have to go, he says wait hold on & carries on, he says doesn’t it sound good , you save R30 I said sure but sounds like a ****. Next thing he says ok you’ll receive an sms. I didn’t agree to this. The sms said to confirm with the bank by a specific time but there was no email or any details on this new plan they forced on me. Then all of a sudden it was activated when I didn’t confirm anything. Now I’ve been calling for days they just keep putting me through to the next person for me to explain everything from the beginning. No body can help me. I want them to listen to the voice recording and show me where I said I agree to this. am I stuck now with a 2 year contract? This is not what I wanted. Why would I upgrade and pay instalment fee just to downgrade to 40gb for around the same price. My time and energy is depleting over this. I wish it could just be reversed back to the contract I actually signed for! Now I’ve paid R200 instalment fee 2 months in a row!! Ridiculous! How am I going to get refunded ? I’m taking this to the national consumer commission..