I’d settle for a discount. Win-win-win (you get money back, the retailer keeps the sale, and there are no transportation costs/emissions).
The feature changes are largely the LCC fimware (and longer valve bodies for steam/water), so it’s an upgrade that is very unlikely to have been bodged by the retailer. BTW, the V3 changes were made from May 2021, so is it possible that the machine actually was ‘V3’ (unless of course the retailer told you they upgraded it).
If the latter is the case, and that was not disclosed at sale, I’d also think twice before buying from that retailer again.