Sorry, Beakybird, if it seems like I was insinuating you were engaging in highway robbery. There is nothing dishonest or immoral in what you are doing. I can see you have had an unfortunate experience and consider it would be fair for you to recover all or most of your investment in the Solton X1. Solton should have given you a shortened warranty on the new X1, let us say 3 months. It is unfair not to extend a warranty when a product is defective throughout a warranty period. Even a three-month warranty would have enabled you to recover most of your investment.
I was "insinuating" that your expectations were unrealistic. However, with your explanation about the careful checkup by Solton, your offer sounds better.