Yeah, that is not a cheap bit of kit. For that money, it's kind of balls for everyone to shrug and say, not our problem.
Honestly, whoever caused the damage, you paid top dollar for something that was undoubtedly waaay marked up. At minimum they should take your word on it (I'm guessing you don't have an established history of this -- why/how would you???), offer to replace, and if they really want to be hard-guys about it, just charge you a "restocking" fee, or whatever.
You'll still get stuck paying for shipping twice anyway...
On that note, while I hate to be a "the customer is always right" grandstander here (a distinctly American view, I think), given the costs involved, and the very defensible claim that it was NOT your fault, I'd call corporate and demand satisfaction.
BTW, assuming I'm reading this right, looks like they are a 9M/year GBP company with a lot of debt -- but are still raking in about 2M/yr GBP... they are probably starting to screw customers in the name of their bottom line, which is (unaccptably and unfortunately) easier for companies to do than sell better products/services...
Victoria & Albert Baths Limited - Open Company
Ya know what, they can still afford to make things right with you. Call and try to work out a better deal lest complaints be filed, social media rants, etc.
Good luck!