Yes, your saga continues...but I find it is now pedantic. The RSC will not be drawn into pressure testing the damaged watch case. My suggestion won't be welcome but you asked...
If you had authorized the original quote you posted over a month ago then they would have been glad to test the watch with a new case. But, I wouldn't pay those prices either - so we agree on that point. Your choice is to move forward and then have it pressure tested later for the horrendous cost of an additional £10 or risk a raindrop
I'm surprised that you're amused.
And one Watch purchased plus one service done in 27 years wouldn't fit any definition of a " day to day" customer.