On each corner, write:
> Quality Work > Timely Delivery > Economical Price
You're ONLY ever allowed to choose TWO.
> If you want quality work produced in a timely fashion, then expect to pay top-dollar.
> If you want work turned around fast and don't have any money to spend, expect the quality to be crap.
> If you want quality work and don't have a big budget, expect it to be attended to whenever the the service provider has some free time.
It is a maxim of business that you will never escape.
This is true of any profession, and is especially true of both programmers and designers alike.
If you are paying proper compensation, you should never have a problem getting quality work, by a designer that makes delivery of your goods a priority. Perhaps you found a bad apple, and that is unfortunate. If so, then the market should weed them out in time. But you say the designer did great work, and it sounds like they had plenty of good-paying projects elsewhere and you simply got back-burnered (and they were not candid with you, as they should have been). I've seen it happen a dozen times is every line of work.
----------
I forgive you for how you came across in your initial post. I'm also told that I'm a friendly fellow who sometimes comes across as... blunt, in writing.