poor service

On 22 March 2019 Mobiles Plus phoned me saying my cellphone contract can be upgraded, which we did. 2 weeks later the new phone was still not delivered. I phoned them and was informed that that specific phone was not available. They asked me whether I wanted a different phone or if I wanted to cancel the contract, I told them to cancel the contract . Up to today contract at MTN is not cancelled although Mobiles Plus insists it is

Can't get any answers from them for the past 2 months