I'm having a similar experience with a very sweet but "older" couple, estimating them to be in their mid-70's. They've sent me long lists (via text) about what's not working, i.e., the front door deadbolt is sticky, the mini fridge door closes just fine but I could re-install and make it perfect, no stove (clearly in my listing), antique armoire skeleton key does not work (it's a 200 year old armoire, it's decorative), no nightlights, etc. etc. I live in Southern California, a desert climate, and when it rains the wood expands and retracts according to the humidity level. It's a constant and everything goes back to normal after the rainy season. They pointed out suggestions for re-arranging everything from my bed placement to the wattage of my light bulbs (brighter please for older eyes) to installing railings in my shower and on the side of my toilet for balance. They also wanted to deliver this list of improvements on a Sunday morning at 8 a.m. (my only day to sleep in). I sent them a $50 refund as a token gesture but they refused (which is fine) but now I can't tell if my gesture was offensive. Overall, I just think they would have been happier in a hotel.
I do not want to discriminate against older couples, but in the future I will be sure to reach out via message and let them know my guest cottage does not have certain amenities and give them the opportunity cancel within their 48 hour window.