Yep, rather painful and expensive exercise that was.
But at least it's done.
I've been interrogating Mr Google and found I can buy a sewer jetting system that attaches to my pressure washer for a third of the plumbers fee.
There's one on the way, it'll probably sit in the shed for quite a few years, but, I'll be armed and dangerous when required.
we had a blow back situation in the kitchen once..it was awful ..black sludge...turned out there was a blockage caused by next door neighbour who had been pouring fat down the shared drain ! GGRRR... made sure she paid for it to be cleared !!