Need to fit reducers, 22mm to 15mm

[ledonc]

I need to replace my leaky old shower valve, but it has non-standard inlet pipe diameters. The inlet pipe diameters on my old shower valve are 22mm, but all modern valves use 15mm inlet pipes.

It was suggested to me that I buy a new shower valve with 15mm inlets and find a plumber to fit a reducer - 22 to 15mm. So I have 3 questions:
Anyone on this site able to do this job? (or know someone)
Are there any problems I should look out for (eg: reduced pressure)?
How much disruption would it cause to the bathroom walls etc?

Thanks

 

[footprints]

A picture would help to suggest a solution.

 

[polesapart]

Not really the right forum (try plumbing and heating) but

if it's an Aqualisa as I suspect you may be able to get a replacement cartridge/seals from them.