First off, I've moved to London from Australia so I'm very unfamiliar
with how things are done here plus I dont feel comfortable with
anything involving electricity at the best of times.

We are renting a flat that has a Triton T80si power shower installed.
It has never worked for us. The electrician looked at it and thought it
was the fuse so he took the fuse, said he'd be back with a new one and
we have never seen him again (luckily, this is a second shower...). I
figure if its just the fuse I should be able to replace it myself but I
dont know what type of fuse to ask for or what shop to go to. Can
anyone help me? I'm in Ealing, if that helps.