Showing a house for sale with tenants occupying

[Dana Holland]

My house is currently on the market for sale.  There are tenants in until the end of this month.  In their lease contract it states that they will allow the house to be shown to prospective buyers/tenants with 24 hour notice. 

A brief background on the situation.  The tenants moved in last December and signed an 18 month lease.  Admittedly we did not do a good enough job of screening them and they became super high maintenance "professional" tenants.  (Lessons learned!) They complained about every little detail and always pointed to the "signed lease agreement" when asking for things to be done for them (which we always complied with).  They got really out of hand a few months back and we gave them the "happy clause" option, where we told them they didn't seem happy and could get out early with no penalty and they took it.  In accepting the early lease termination, the tenants sent us a note agreeing to vacate by the end of July and said they would comply with the lease agreement and make arrangements to be off property with their large dog for all showings with 24 hours notice. 

Fast forward to the beginning of July, and when notified of the first showing, tenants responded that they will be home for all showings and to have the realtor knock before entering because of their dog.   Pretty annoying, but ok fine.  A week ago, they were notified of a request for a showing that would have been 21 hours after the notification.  They balked and firmly stated that as it does not comply with the 24 hour notice and would not allow it.  Since that is stated in the lease agreement, although annoying that they aren't even slightly flexible, we understood that they are not obligated to help us out.  However, yesterday they were asked to allow a showing for tomorrow (so 36+ hours of notice), and they said the time isn't convenient for them and are not allowing it.  They gave an alternate time, but of course that doesn't work for the buyers.  I have a feeling for the rest of the month the tenants are going to only allow showings when it's convenient for them (which most things are not convenient for them).

I don't think there is anything we can really do about it, but just thought I'd ask here.  Any suggestions?  I'm not really into paying them to comply because we've given them a lot throughout their tenancy (more than obligated), and knowing them it probably wouldn't help too much anyway. Do I just have to wait until they move out to really start showing the house?