faulty phone

I signed up a contract with mondo in December 2015. After receiving my cell phone and using it for 3 days , the phone stoped working. I phoned mondo customers centre and sent numerous emails , thay told me thay would send someone to fetch my fault phone and replace it with a new cell phone. Im still waiting months later and they are still deducting money from my account for something I can not use. Im very unhappy this is shocking service.