Hi Scraping!
I can see Hammy’s answered most of this for you, and as always, he’s spot on.
In terms of the cost of a new one, well, the T-Classic Desire isn’t in the current catalogue. Assuming it’s a 3 hand quartz watch with date, then around £300 or so, perhaps say £275 to £325.
So, you might think ‘well, why pay £105 on a full service?’
I’d say it’s a good deal, because you’re basically having your existing watch returned to new condition for a third of the cost of a new one.and increasingly, Swatch do just drop in a brand new movement. And you still have 13 years of memories with your watch.
Hope that helps.