Frontier Airlines complaint: No Notification of Schedule Changes

We traveled on Frontier from DAC to LAS on Sunday April 10. Our original flight was for 7AM. It was switched to 6PM. We were supposed to get into Vegas at noon. We didn’t get in until midnight. We were not informed of this change and I found out when I went to check the itinerary on Friday April 8. This caused us extra money for hotel. We were meeting a couple who traveled on American with not difficulties. However, since they were our guests we had to scramble to help them since it was their first time to Vegas.
We traveled back to DAC on Sunday April 17. At 6PM on the 16th I checked the itinerary and we were to leave Vegas just before 9 am. I always get to the airport early and good thing we did because our flight had been moved up to an 8 oclock departure.
My complaint is the in I did not receive any communication at all about schedule changes from Frontier. No text, email or phone call. We also lost a whole day of vacation due to getting into Vegas 12 hours later than we planned.
I would like to know why I should ever bother to fly Frontier again. What steps will you take to rectify this situation.
Thank you.
Respectfully,
Mike McClurg