Just seen this-my condolences. Had a covid issue with this shower. They are in breach of Consumer legislation and the recommendations published during the first lockdown.
On a practical note did you use a credit card. If so a couple of options including Section 75 claim. Might also be cover on travel insurance, although not sure how it would work out since you appear to be seeking partial recovery.
Plenty about Solmar on trustpilot.

Can’t you just work harder and longer and go next year