MTN SA bunch of *******

On the 9th of April I received a new router package it didn't have coverage connection, I took it back on the 10th they changed to another package at newtown junction mtn which has the same problem of coverage. I then returned it and canceled both the contract on the 30th R970 was deducted from my account after I had canceled prior the company invoiced. They then logged a refund which was supposed to be paid in 7day according to their staff a lady by the name of boitumelo moerane. Update i haven't been paid back my money and when I call mtn im being taken from pillar to post. The reference number of my query is RITM***. Shame on mtn I was billed and paid for service that was not rendered to me you are bunch of ******* how does one invoice for services that are canceled and refuse to refund my fund.