Drop the client or give another chance?

So I do doggy daycare and overnight care in my home. I have to say that I've been successful so far and all the clients I've had absolutely love me.

I have 1 client that has two dogs. When I first started to watch them I was a bit overwhelmed with their request. More so specifically, they feel like i should have no other client drop offs when theirs are here. I limit how many I take in so each animal has adequate stimulation time and so there is no over crowding. They also believe I shouldn't have my door open (I have a screen door I leave closed) there was one day he was picking up and I was trying to move my dog back plus one more. One of the dogs opened the door but I was watching and they went straight to him. I got a "nice" txt saying I need to be more alert and not have my door open. I understand her point but she also doesn't realize that her dogs know to stay in my yard as ive been training them to do so and also when we go on potty breaks I can untether them and they go straight to my door.

I also gave them a discount on both their dogs this previous time they booked because they booked for around 8 days in advanced. Here is where my problem is coming in. The last four days, he has been running late by a min of 15 min each day doing drop offs. I am pretty flexible on time but I've also got school going on and appointments myself at times. I mentioned today about him being late but he kind of just blows it off and tells his wife then his wife has a firm discussion with me.

Should I give them another chance or just let them go after this booking is done?