We were in your exact position about 7 years ago when we arrived at the villa we had rented to find it was listed for sale. We were notified by the management company that they would be showing it the very next day! I politely informed them that we would honor that booked showing but that they should give us at least 24 hrs notice before the next showing, as after all they had not informed us when we booked in good faith that our villa was up for sale I now google any villa we rent to check whether it is listed. Luckily, we were travelling with another couple, and they stayed back to be present during the showing! We were concerned about potential theft and security issues. We picked up the place but felt no necessity to clean the villa as you would if you listed your own place! Turned out that was the only showing when we were there for the week, and it turned out to be ok. We did feel uneasy for the week though, never knowing who had been in the villa when we weren't there. You definitely feel more secure when it is bonded employees of the management company entering the villa. My tip would be to let the management company know you are not happy with the disruption to your vacation. They may back off the showings and schedule them when the villa is not booked.