Can't do their job

We immigrated. I am now trying to cancel my phone contracts. I have 4 numbers with MTN. 2 data contracts and 2 with phones. I am trying to cancel the data contracts because we will no longer be using it, but I will still pay the remainder of the term for the two phone contracts.

I however sent them multiple emails to help me to cancel but they just don't want to. Their excuse is they can't reach me on my phone number.. after I told them I moved abroad so they won't be able to contact me. Then they just ignore me. So at the end of the day I need to continue with payments because they just don't want to do their jobs.