Terrible service

I app**** for fibre service and they sent someone to come and install. The installer used somebody else's line and my connection was cut within 2 hours of becoming active. I contacted cool ideas to alert them and they used their favourite phrase "We are investigating" for a whole 3 weeks. Cool Ideas still could not find fault with my line after all their "investigation". Eventually someone came and fixed it and now they are demanding I pay for a service they did not offer to me and telling me that my refund may take 6 weeks. I want my account credited and not be demanded to pay for a service I did not use or they must cancel their contact and give me money back.