Should I change the cambelt on my SEAT when I change the water pump?

My 2019 SEAT Arona (18000 miles) water pump is leaking. When I get it replaced should I do the the timing belt at the same time? I have been quoted £899 is this reasonable?

My indicators and windscreen wipers start on their own - what's the issue?

I have a Renault Clio MkII. The indicators and windscreen wipers start on their own. They also go at different speeds than they should.

I can't open the back doors of my car, what's wrong with it?

The central locking on my Vauxhall Meriva isn't working. I turn the key once to unlock the drivers door and twice to unlock the back and passenger doors, however only the driver's door will actually open....