Hi, I can't see any answers but we have the same problem and a colleague of my husband's has suggested this:Triton Pressure Relief Device - 82800450, I found this at showerspares.
He says the hose probably got twisted and made the device fail but there's another one the same so be careful! Let me know please if you fixed yours. or maybe we can attempt to fix them together!
janiceeast@sky.com
jan, December 2008