I had the same cleaning service come in and clean my house for the past year and a half. Every two weeks they come in and clean.
One time, early in the relationship, they did a very poor job. I wasn't happy so they offered to come back at no-charge next time. No excuses, just great service.
I became a fan and advocate, told friends and neighbors about them and the relationship continued. I even blogged them for their superior commitment to client satisfaction.
Today they cleaned, per our every two week schedule.
Frankly, it was the worst cleaning job I had ever seen. It was so bad, in fact, that the house had to be cleaned again.
I called to let the owner know about the poor job done. She started making excuses and told me what they do and do not clean.
That prompted me to look at everything closer. Guess what? It was worse than I suspected. Bathrooms not done, really bad.
So, in the immortal words of Donald Trump -- You're Fired!
When you have a good client, take care of them. Don't let down because you think they will be loyal, no matter what.
Always remember, you are only as good as the last service performed. If there is a problem, fix it without argument.
The reward is a stable of loyal and happy clients who use you over and over again every year.
Remember, backend sales is where the REAL money is in business.

