there's a great story in Private Eye this week... officials were cleaning up after a festival in Frankfurt and connected all the portaloos to a pipe to empty them, but accidentally connected the pipe to the U-Bahn maintenance pipe and pumped 2000 litres of raw sewage on to the platforms of an underground station. It had to be closed for cleaning.
Sugar. I went to have a wee thinking that the effluent goes straight out. Toilet filled up and overflowed the basin all over the bathroom floor, started coming through the kitchen ceiling. Rang again - "we though we'd come on Monday" - I think not. Waiting for call again. now it's an emergency. Had to switch power off as water running down wall in kitchen. Stopcock off on incoming water, all now serene, if wading. Glad we have lots of towels. We have done a deal to use our neighbour's loo.
I had a problem with my drains a few years back but lucky it was contained in the garden and easily resolved by cleaning out the drain covered by the manhole.
YaaaH! Bit of a mess, but he's managed to sort it, he said that following the Monday episode, it seems to be that the was not enough water flowing through the toilet papeer, and when they jetted the pipe , it cleared the blockage, but then stuck in another place in the run.