Inner wheel re-furb

[TTwiggy]

Hello all, a bit of advice if you please.

I have a leak in one of the new tyres that has just been fitted to my Boxster, and I have been told that it is due to a corroded inner wheel rim, causing the seal between tyre and wheel to not be airtight.

Does anyone know where in S.E London I might be able to get this sorted, given that it would also need to be somewhere that can remove and refit the tyre?

Many thanks in advance.