It does sound like quite a lot @VibesCurator but sadly, this is what you are going to be paying these days. You could put them in a dogs boarding kennel but that is very likely to not be much cheaper. Especially if there is more than one dog. I am going to have to say that YABU though, because I think this price is what you should be expecting to pay in 2025.
As has been said, these dog sitter people are taking time out of their day to come to your home, (and spend time with your dogs,) they are incurring travel costs, they are feeding, petting, and walking your dogs, and cleaning up their shit, and they will have to allocate more time if the vet is needed for some reason, and many people want the sitters on weekends and bank holidays.
One sitter in my village looked after the dogs of 4 different families (2 families in the village and 2 families 4-7 miles away,) between 20th December to 2nd January, (all 4 were at least 5-6 days,) so she was doing her job Christmas Eve, Christmas Day, Boxing Day, New Year's Eve, New Year's Day. (As well as all the other days in between.) She couldn't drink as she had 2 visits per day, and had to drive to some of the dogs ... So she was working all over Christmas/New year.
I think £40 a day is actually what you can expect to pay to be honest. You need to factor these new/higher prices into the price of your holiday. Obviously if you're away for 10 days, that's £400 extra. But this is the price you pay for having dogs. Are the kennels not an option? They may be a bit cheaper...