My money not returned in time

I'm very angry at mtn... They should never make promises they can't keep to their customers. They double debited me and failed to return my money in time. They problems are mine now cause I'm sitting in arrears because of their mistake... The only thing I'm going to get now is \sorry sir we will try sort it out asap\". How is that going to help me cause I lost money cause of them. It is unacceptable. They should even keep their apologies unless they going to pay for everything that bounced off my account..."