Sorry to hear about your experience, OP.
I've had many terrible experiences as well. And sometimes repeating multiple times leads to worse service, as the provider becomes complacent and feels that she can get away with putting in less effort. This is because you keep coming back, no matter what.
It seems that you had some feelings/connection with her. Hence the repeats and gifts, something that one normally wouldn't do unless they really cared about the person. Also, I can sense the hurt (understandbly) that wouldn't exist if you had no feelings for her.
The sad reality is that escorts generally do not reciprocate those feelings. Your gifts, such as flowers, would be well-received and appreciated by your wife (if you have one), but not most escorts. Flowers have no practical value, and are generally thrown away and not appreciated.
$600 for 90 minutes is a lot of money, and as a repeat cllient, who just brought gifts, it would be reasonable to expect good service. The fact that she didn't dress up, casually tossed the flowers, then talked on and on about her next clients reveals the painful truth: she doesn't value you as much as you'd like. Actions reveal one's true thoughts and feelings. To her, you were not as important than the other guy that day. The real catch is the guy who booked 5 hours and presumably will pay at least $2,000.
Of course, her attitude is completely wrong. She was probably so excited and could only think about all the money she was going to make, and had to share it with someone. It was very poor judgment to share it with you.
Her actions after the event also reveals another truth: she was genuinely sorry and felt terrible for the way she acted. She refunded the money, apologized, and I believe her when she said she didn't realize how much she took you for granted, and that she couldn't enjoy her next date.
If I were you, I would give her another chance. I do think that this event should alert you to the fact that she doesn't have feelings for you, however you feel about her, and that from now on you should enjoy the sessions without any expectation of reciprocal feelings beyond that of escort and client. She viewed you as a good client who she was comfortable with, and could share her thoughts with. In a sense, it is a good thing that she is comfortable with you. However, she crossed a boundary and realized it.
Now that this boundary has been established, perhaps future sessions will be better.
I suggest you book one more session to see how it goes, and take it from there. There is nothing to be lost, really, at this point. However, it seems this lady is very special, and it would be as shame to rob yourself of any future pleasurable experiences because of what may have been a naive misjudgement on her part. Many escorts are in the position they are because they lack certain skills. Some may be on the spectrum, and lack social skills and judgement.
Whatever you do, I wish you all the best.