Hi,
Just thought I'd follow this up. Now unblocked!!
I Cut a hole in the pipe (like a slice of melon) on Thursday evening. Stuck the drain rods down, got to 30ft (and off my boundary) and came to a bend in the pipe, but no blockage. Couldn't explore further, so called in a jetting company.
He came Friday pm, gave everything a good blast on my boundary via my hole, but no joy, then went to the main sewer manhole tried to jet but got nothing but gravel and soil coming out, suspected collapsed drain. He said the problem was on the water board's side, so phoned them.
They were supposed to come out on Saturday, but from reading the rules I was convinced the problem lay on my pipe, therefore my problem, so phoned the home insurance (covered for collapses, but not blockages). They sent a surveyor out, who also said it was the water boards problem, so he phoned them.
They finally came out Sunday pm, went down the manhole, stuck a jetting pipe in where my drain joins, gave it a few metres, and 30 seconds of water, and out floods the mightiest pile of **** i've ever seen. The blockage was caused by a ball of kando toilet pipes the size of a melon. They are now banned in my house.
Thanks for your messages guys!