Replaced the Screenwash Bottle today (other one was busted from an Accident a week ago). I'm still using my exisitng pumps which work fine however when i use the Jet to the front windscreen I am also getting water at the same time on the rear screen...if I operate the rear screen wash it works exactly as it's supposed to. Slightly puzzled why the windscreen function is also sending water to the rear. Any ideas ? could i have put the pipes on the wrong side of the Pump perhaps would that maybe cause this ?

I could be wrong but doesn’t one pump do front and rear washer by reversing it’s rotation and the other pump do the headlight washer every 5 cleans of the windscreen
So maybe crossed pipes
Hope that makes sense

Yes that's exactly what it does. Have done a little more research and think i may have found an answer....the Pump that does the windscreen and rear window does indeed reverse, however it seems to have 2 Outlets 1 to the front and 1 to the rear and what appears to be some kind of device that slides between the 2 outlets presumably to block the water from going to the Windscreen when you want the rear and vice versa, sort of like some kind of Diaphragm.
I'm guessing that it isn't fully blocking the water going to the rear when i want to do the front windscreen, it was working fine before some idiot impacted his Merc into the front of my car hence the Washer Bottle getting Knacked, and as far as I can tell the Pump doesn't appear to have suffered any damage unless the Impact knocked something out of Kilter inside.
Going to wait till the Washer is almost empty and switch out the pump for a spare and see if that fixes it, then see if I can repair the other pump to keep as a spare.