Well, UU came and tried rodding it with 2 different sets to no avail.
So they jetted it, threw the CCTV down and there were lots of roots breaking through.
So they cut them off and explained it was up to their management how they wanted to deal with the situation: either sleeve the pipe or come back and unblock it as needed.
This am I got a call from UU saying they are going to sleeve it.