I wonder if anyone can give me any advice.

I recently moved into a house and found that the electric shower
cycled between hot and cold. Thinking the shower faulty I replaced it
with a Gainsborough 8.5kW shower. Unfortunately, there still seems to
be a problem. The water pressure is fine (as far as electric showers
go) but I seem to be unable to get it to run cold. Even when I run it
on low power and minimum on the dial, it still puts out water which is
slightly too warm for comfort.

Does anyone have any idea what the cause might be? (I am confident I
have connected it the cold water supply, it was a take it out of the
box and wire it in sort of affair).

Thanks.