KCS internet

I sign a 24 months contract with kcs I payed 1300 for installation of WiFi ,they installed a faulty router that has been giving me poor signal have to report it every week with no help I ended up asking for a manager that’s where my complain was taken serious, so they came into to my house they changed the router but still was receiving the same thing I reported I decided to terminate the contract since it was bridged by them by not providing what I was paying for so now they want a cancellation fee of 5000 while I was paying them for the past 17 months without internet