Shower

[rogerrog]

Hi guys, I already posted a thread before with regard to a shower force 3 bar pump switching on and off. I did take your advice and contact the manufacturer (with many thanks). They said to take off the switch from the outlet and clean it up. This done, and just as I thought this was only a temporary fix. The prob came back a couple of days later and is still ongoing.
Does anybody have any idea to remedy this? The instructions say that you cannot install a non return valve on the pipework anywhere at all, so I do rule this out.
Please help!!