Hi
I had a great response with One Stop Drain Unblocker recently.
Best buy 2-3 bottles.
It is basically Sulphuric acid, pour it in and it will disolve the organic material.
Pour into bath & sink plug holes and the bog, wait half an hour and then wash through.
I added hot water to mine and it reacted violently, so be careful with hot water, although it really flushed it through.
Spirit of salts is good, 32% Hydrocholic acid, but the other stuff is stronger.
Costs about £5.99 a bottle large)
Have at it!
Regards
Martin