What I noticed when I traded in mine, is that they usually are quite aligned with eurotaxglass.ch.
Make a check before you discuss with them, just to have an idea. The SS price, if it's the one that was on autoscout24 some time ago, is aligned with the price of mine.
It is the one on autoscout
It all comes down to price to change - I have a figure in mind - if they can close to that I will be happy. If not I will walk away and leave it for another year.
(OK - I probably won't)