Pathetic service

So my sister Nolubabalo went to MTN Centurion Mall to get a router , then it took long for them to get back to us about the router which we needed for our children's education, then I finally made a plan n got another one then they get back to me after someone came back from leave , then cancel the contract but they are still debiting my account 5 months later because they can. Where is the customer service in this business??