How do I fix my Triton Opal Shower?

My Triton Opal powershower is approx 1o years old and suddenly started spraying water out of the joint where the shower head meets the unit. There is a clear plastic tube that runs parrallel to the shower head feed within the box, and this has started gushing water suddenly. Initially thought that this had popped out of a fitting inside the unit itself, but having opened the unit it looks like an overflow pipe and that the fault maybe more complex than I thought..... any ideas / support would be appreciated.