Terrible service

I migrated my line from ADSL to Openserve Telkom Fibre and after it took them 2 month to come and install. My line is terribly weak. I am paying for a 50mbps down and 25mbps up but I am getting less than 10mbps for both . I can only add one device and if I add more to the wifi it says not connected . This is when it actually pics up the network . Most days it just says no networls available. During the installation the installer did not have a router and he gave me a second hand router and he said it was his . They said I was going to get a new router with installation. When I called him to bring the new one he said I must keep this one it is fine implying they are not giving me a new one . THIS IS ABSOLUTELY HORRIBLE IF MY LINE IS NOT FIXED WITHIN THIS WEEK WITH THE CORRECT SPEED I WILL CANCEL MY CONTRACT . I have been with Telkom for more than 2 years and they like saying you can not breach a contract but thry are breaching an agreement because I am not getting the service they promised which puts them in breach of contract.