Can't even cancel contracts anymore

I phoned to cancel my contract, spent over 20 minutes with an agent constantly wasting my time to get me on another deal, told them wanted the contracted cancelled which she said she would and offered 1GB WhatsApp bundle to keep the number in use which I eventually agreed because I was told I could cancel it anytime.

I recently looked at the app and my messages, they only cancelled the contract cover and left me with this extra bill to pay, I tried calling the other day and spent more than 15 minutes waiting to no avail.

Cancel my contract and stop wasting my time.