1.) ABSOLUTLEY invoice her for the time you already spent. The coupon is a good idea. Also, Snail Mail is a good idea for ALL invoices. Paper trails are a good idea if you ever have a customer who does not pay.
2.) Send your recommendations along with the invoice. You are the lifeguard and she is the drowning victim. If she does not want to heed your advice/help... Its her loss. Don't take it personally. From what I see, if she says anything bad about you to others, she will be a liar.
3.) Don't sweat the stuff you cannot control. I.e. A client with a crappy attitude. There are always going to be those who don't like you for whatever made up reason. You cannot control that.... Bill her for your time and move on.
Good Luck!
"Unlike most of you, I am not a nut."
- Homer Simpson
"If the enemy opens the door, you must race in."
- Sun Tzu - Art of War
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