Bad service Telkom

We have/Had a ISDN line with Telkom that has not worked since late last year after months of trying to get them to fix the line without luck we cancelled the service....We are still waiting for them to cancel and refund us. They collected their ISDN box 3 weeks ago...We got a call from a Telkom person by the name of Nu saying they where refunding us from last year Aug 2014 still nothing NO line No Fix No refund....Actually they still billing us after collecting their equipment....Can some please help I am at the end of my tether with this situation ready to start legal action again Telkom which will now include our time spent on this issue.