Poor service from MTN twitter handle

Had a complaint about incorrect billing on 28 Oct and communicated it with the @MTNzaservice twitter account. After weeks of back and forth they agreed to refund me but they didn't. Got in touch with 2 weeks after that and they said they had already refunded me, which never happened. Told them and they said they will check. Asked them a week later for feedback and they rep**** a week after that saying they are still checking. Its been 6 weeks of this back and forth and I feel like MTN is just taking me for a ride. This is the worst customer service ever!!!