I just wanted to tell you my story, which is very similar to your parents.
We booked to go away and like you we booked early, in fact a year early as we were travelling with my parents whom have walking difficulties and needed to ensure we got an apartment in a central location. However, the evening before we were due to depart, we also got a phone call telling us that our apartments were under refurbishment and we would be moved to another hotel or get a full refund. A refund was out of the question,we had taken time off work and wouldn't want to disappoint the kids.
We decided to opt for the new hotel and checked it out before the shop had shut. I was concerned, the hotel seemed quite far out and I wasn't sure if my parents would be able to walk the distance to the resort and we didn't see why we should have to pay for cab fares.
I contacted the Travel agent and they said due to the lateness of the information they were unable to offer another option and besides they were about to close....charming. I accepted it but told them I would be asked to be moved if necessary and told them I would be putting in a letter of complaint.
Well, when we arrived we soon realised that this hotel was not for us, it wasn't suitable for kids and was too far out, about half hour walk to the resort. I complained to the rep and he showed no interest, saying to put it in writing on my return. We decided to make the most of a bad situation.
Whilst there I decided to take a look at the hotel we were due to stay in, just for future reference and soon found out that there was no refurbishment going on, I even asked the receptionist.
On my return to the UK I wrote to the travel agent and asked for compensation, they offered us £100 between 7 of us. I contacted Ros (solicitor) and she explained that we had a good case and took it on for us. Well, thank you so much Ros, Ros managed to get half our money back, which we were all so pleased with. What a difference hey.
Lets hope you also have a good result.
Sue