They are probably unaware of the dogs distress, pop a nice note through asking if they know - it may be a new thing following the move.
Leaving dogs outside is risky, leaving dogs in with access to outside is risky unless your garden is SUPER secure.
In any case, dogs upset by being left are not any better with access to outdoors, dogs do not run around gardens playing and amusing themselves.. they dig holes, bark, try to escape, chew stuff.. same as they will do indoors if not happy being left!
Greyhounds...... steal things off work tops and are big strong muscular dogs. Anyone taking on one and not expecting that is a bit feeble minded I think!
They are delightful dogs but consider them institutionalised and mentally backward, because when pet dogs were learning about the world... houses, cars, stairs, other dogs, washing machines, prams, hoovers, dogs that look like cats, dogs that look like donkeys, small children, big children....... etc.. All a greyhound has learned is.. kennel, paddock, van, race meet, trap, track, other greyhound.
So introducing a greyhound into your home means a lot of work slowly introducing all the normal things, which takes time.
Also whilst greys are typically used to not having direct human contact for most of teh day, they are ALSO used to being kennelled with a friend, not left loose in a house, and they are used to people coming and going, sounds, other dogs being moved around etc - so the total silence of an empty home, filled with unfamiliar stuff and free choice to do.. whatever...
Expect to come home to a repurposed sofa, dug up carpets and wee/poo all over.
If I were taking on greys now ... I'd get a kennel pair direct from a trainer, dogs who have genuinely been kennelled together all their lives. Crate train them and I'd have as long as poss off work to settle them in then get a dog sitter for my return to work and gradually ease them into being left. Done this way there are far fewer problems.