Jay
If it were me, and I was starting from scratch, I would:
1. Keep these customers. If you bin them, then you won't earn anything more out of them.
If you keep them and next time round only half want it done, then it's still money you wouldn't have had.
Keep them until you can afford to bin them off.
2. More importantly, change YOUR attitude, DON'T take it personally!
The reason these people are a problem is because YOU are letting them be a problem.
They are just numbers and addresses in a book that could potentially earn you money.
Yes, you did a good a first clean, gave them a good price and made sure they were happy with your work...and now you feel they've let you down.
Welcome to window cleaning
Think positive, think how you can use these crappy customers to your advantage (possible rainy day, when a decent custy may whinge, or on a Saturday where everyone is home and you may get 2 other enquiries from people seeing you in the same street).
You have to be positive; the hour you've spent getting annoyed and coming on here, you could have been out canvassing and leafleting.
Get it sorted!
Having said all that I still get annoyed with custys; (poxy stick on bird feeders) what's all that about!