Poor customer service for a new client

I app**** for the data sim only contract from MTN. The card was delivered on the 12 Jan 2021, but the sim has never worked ever since. I never received any instruction on how to activate the sim nor what is the number. I went to the store to cancel the contract and they told me to phone 135, of which I did but was on hold for 35 minutes. @MTN I want to cancel the contract that has not served its purpose for +7 days.