So, I carried a yoga ball into work, blew the blasted thing up and have now been told that due to Health and Safety they won't let me sit on it.... Grr
I "can have anything I want" instead. Hmmmm 
Only 5 weeks at work left - anyone got any suggestions for alternative seating. My tailbone is numb though that's probably because I am desk bound and not taking enough breaks more so than the quality of my current chair.