Worst customer service ever!

This has be the worst experience ever. They double billed me and called them back to rectify their mistake. every time I called in they said they would rectify it and nothing has happened. eventually I logged a refund only to realize they would not refund the entire amount claiming it would be credit however I never agreed to that. Spent close to 2 hours collectively on the calls I've made to them, and each time have to explain to the consultant and each time they say they will get their manager to call me back. I am currently still waiting for a call to rectify this and its been close to 3 weeks. Worst customer service ever!