Cost to service a ladies Constellation Gold 1391.71.00

I purchased this watch in 2000 (not that it's relevant but at a store at the top of the Swiss Alps!) and my wife has not work it much, I would say about on average 3 months/year. Took it into an authorised service agent and they, upon inspection said, it would cost about US$1K for the services. Since there are many parts to replace, they would send the watch movement back to Omega who would return a new/refurbished movement. The work would include installing and adjusting the new movement, new gaskets and seals, crown assembly and a general clean. Two years warranty.

I am pretty relucant to do this so after asking AI (!) had advice that any competent horologist could do this work. I wondered if they could get parts for the watch and was AI said since the watch uses a standard 2520 movement, independent watchmakers can easily buy standard ETA 2000-1 components through global material houses (like CousinsUK, Esslinger, or Otto Frei) without ever needing to deal with Omega directly.

I went to a local place that services Omega, Rolex etc. but are not authorised and they advised it could be done for about US$500 but that would be only a one year warranty. They would not polish the case etc. unless asked to because it might remove some of the coating. Interested in folk's views on this

It's my wife's watch and she decided to let the authorised agent do the service and be assured they get genuine parts and the two year warranty. Of course I will be the one paying for it :-(