We have used costablanca-holidays with no problems. I have booked with them for the first week in April, but I was concerned about the early check out, as we have a very late flight back. We phoned them and they said we can leave the suitcases in the apartment for as long as we need to, but not to use the facilities after 10am (ie, shower, as it will have been cleaned).
They will send you the key at least a week before the holiday too, which is so much less hassle when you arrive and we have always found them very accommodating and generally nice people to deal with.