@Brian686, unfortunately, that happened sometime, my advice always offers to send a cleaner or yourself to go and apologise. If they refuse ur offer u are cover as u tried to solve the issue., The best thing is to be proactive. When things like that happened I always make sure I come up with a solution, and fast so he does not leave any room from guests to complaints.
not sure if ur cleaning team do it or not, ask them to take pictures after cleaning is over of all major area of the listings, from the fridge inside to cutlery and bed, seating room inside wardrobe etc...
When guests check out my cleaner video the flat + pics if it is in the mess, and immediately what app to me. If guests are 2 and used 7 towels by cleaner will send pictures of the whole towels used etc... Pictures are always handy when they are a disagreement