I'd be polite but extremely firm.
Auctioneers and dealers have to cure themselves of using this word 'restored'. It should only mean a sincere effort to restore something to its original condition. You can have good restorations and bad restorations, but this is the equivalent of sending your Rembrandt off to get cleaned up and it has a big Snoopy painted in the middle of it. An auction house wouldn't call a painting restored if someone had painted a different picture on top of it, and they shouldn't do the same with watches. It's no good them saying it would still be the original dial underneath, it would still be the original canvas underneath the Snoopy Rembrandt, and so what if it is.
You could say that you have consulted an established body of expert opinion (not me, at all, but many of the others on this thread and in this forum). And if they get shirty, you can refer to the reputational damage that could be suffered by an auctioneer who so patently mis-describes what is being sold.
Oh, and buy from the private sales section here.
Good luck!