After the builders completed the college I work at they called in a subbie to replace some extra long ceiling tiles they had fitted as a temporary measure before handing over. The subbie came, fitted new framework and cut down some of the old tiles to fit. That section of college is not in use at the moment due to only having 1/3 of student capacity until next September. A few days after the subbies had left the cleaners were going around running taps and flushing toilets. One toilet kept overflowing so I was asked to have a look. Tried a plunger, no luck. Tried the 'sealed plastic bag' trick, still no luck. Got a flexible length of plastic carpet edging but couldn't budge the blockage, it was solid! Original builders had one of their own plumbers come to investigate and he had to take the whole toilet out. Subbie had rammed a load of off cut tiles down the bog and the bloke who patched up some flooring with levelling compound had dumped his excess down there as well. They are now being chased for the cost of the repairs.