Holiday activities refunds

01zesty01

Hi all just wondering if I have any rights at all for an issue I had on a UK holiday I just returned from. We stayed in a lodge complex and you could pay to do activities throughout your stay so we booked into a few through the holiday company. One activity was through a third party but the holiday company booked us in with them. It was pony trekking - we were advised to arrive 20min early and of a weight limit which we thought we would be under. Unfortunately when we got there we had been told the incorrect limit and we were both over ( pretty embarrassing). They offered us to go in a carriage instead but as that's a completely different experience we declined. We asked about a refund and the 3rd party company said they would get in touch with the holiday company about it. So we left. When we checked out of the holiday the holiday company said the 3rd party company had only agreed to refund one (not both) of us as they had had to prepare the ponies for the day and we had declined the offer of a carriage ride. I can appreciate it's disappointing for them like us but even if they have to deduct from the refund I think that only refunding one of us does not seem fair. Surely it didn't cost them the whole fee of a pony trek to set up the ponies and we arrived really early so they hadn't saddled up yet. Do we have any rights here ?