I think the damage is visible in the photos, just favourable lighting is all. Yours does make it look worse, but there clearly is damage shown in the seller's photos. It's why I prefer to do videos now when selling as it reveals the exact same spots at multiple angles and with the light catching any issues.
Any damage you don't expect will always be a real sting. The seller might refund anyway, and a reclaim of your VAT paid is definitely possible. The handling charge by your courier is likely lost though.