Gainsborough Energy 2000x shower stopped working?

Hi
I'm not sure what exactly happened as to me this shower always worked fine but as i got back home and someone else has used it, I firstly found that the shower wasn't stopping (the dial of the flow -at the top- to either set it to: Stop/Low/High/Medium wasn't working and the shower was going on continuously). Then, I took a shower and while under it, it triggered the main (RCD? not sure the name) to go off. From then, the shower now is not going on at all (I have reset the main back on, in case you were wondering!). Any suggestion if there is something i could do myself, if there's a part I could perhaps change myself or else..? I cannot find the user manual anywhere on the net...any idea? Please help!