I only do month to month leases now, this is a big reason why. The last tenant that was a problem with constant whining was a person that evidently came from a wealthy family and just didn't know anything about living in a house, he didn't know how to mow the lawn because he had never done it before, we replaced the dryer in the house because it wasn't working and noticed the dryer lint trap had never been cleaned, couldn't plunge a toilet, complained about a weird smell all the time, complained that one room was too cold, etc, etc,. It was almost a daily occurrence for him to call and complain about something.
Finally on one trip over there I told him (nicely) that obviously this house isn't meeting his standards and he should start looking for a new place to live. That very quickly put an end to the majority of the complaints as there aren't very many houses this large to rent in our small town and he moved his large family up here so he really would have to cram into a 2-3br house or rent a couple apartments.
Just nicely state you are working on fixing the issue and if they wish they came move out at any time.