Plumbing Problems

i never check the temperature of the sower before I get in it, today this was not such a good idea.

I left the shower running for a couple minutes to heat up before getting in, had a cup of tea then proceeded to get naked and climb in to the shower only to be drenched with freezing cold water.

Now I don't know how to fix it, apparently the switching it off and then on again technique doesn't apply to showers.

I have checked the main fuses but all seem to be working.

I took the cover off the shower unit thing, I think more to make me look clever as I have no idea what it is I am looking for now.

Any ideas?

Now I cant wash until it is fixed and I smell of cat.