From your avatar I take it you are in London (not the one in Ontario...) I have not needed to use any of these myself but there are three standard suggestions in the UK, all with the necessary Omega parts account.
Chris Nicholas
https://cjnwatch.co.uk/wp/
Simon Freese
http://www.simonfreesewatchmakers.com/
Swiss Time Services
https://swisstimeservices.co.uk/
your favourite search engine will find others, these are the most commonly named here.
DO NOT take it to Omega! And make sure your instructions on preserving originality are received and understood.
Lovely watch
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