Can I Change Dentists While I'm Using Invisalign?

The fee is normally collected at the start and should you decide to quit, there is no refund. To change dentists would equate to paying for Invisalign twice. It is likely better to simply finish with the current provider.
Sometimes skipping IPR is not from forgetting, but simply the case did not need it as previously thought. I would not assume this dentist is incompetent.

Hi,
I would recommend that you speak with your dentist about your dissatisfaction of the treatment and see what the dentist can do about it. Different offices have different price schedules regarding fees for new aligners, some offices incorporate them into the initial fee and some charge for additional aligners.
If you continue to be unhappy with your dentist and treatment, you can switch doctors with invisalign, as you can authorize the new doctor to get your case transfered from your old doctor. If you do switch to a new doctor, that new doctor will charge you a fee for the continued treament.
I hope this is helpful!