Absolutely horrific experience. I got to check my bags in and was told that I didn't have a checked bag but I had payed for one. Turns out it was for my return flight. Which isn't a big I was told that it happens often and that it wasn't possible to switch. I understand that with space limitation. I have to add a bag again no big deal except you can't do it in person via cash or card. You have to to do everything through the app. So I add a bag and wait for a confirmation and 10 minutes go by and nothing. I go to the counter and explain situation and that I just paid for my bag. I was told unless it showed up in the app. They wouldn't take my bag and I needed to just try again so I did. AGAIN another 10 minutes go by and no change in my app. I start to cry and another frontier employee printed off a ticket for my bag and told me to go through after explaining that I just paid for it. After I get through TSA I walk up to my gate as it's boarding. I get settled in my seat and then get a notification that I have 1 I repeat 1 bag added to my departing flight. I was super annoyed but whatever the worst part was over...nope. I check my account a few days later and see that they charged me multiple times. I call their customer service number and was treated horribly. They tried to tell me I paid for two bags the one that day and the one for my return flight. I have proof I was charged for 2 bags one way and one the other. I have proof. I have screenshots of my payments and I was told I was wrong and didnt understand what I was looking at...I tell them again I have proof. She starts to get hateful and so I admit I cussed her out for telling me I was too stupid to understand what I was charged for. I call again and get the same type of attitude. No help at all the first 3 times I call. It was only on the 4th call where I was told to submit the pictures to their website and I did and never heard back. CROOKS. The guy at the counter told me to keep trying to run my card till it went through. How much money would they have taken before they admit they were in the wrong. You can't have every kiosk down no way to pay in person then a app that lags by almost 45 minutes. Ohh and they will try to get you to sign up for a credit card on flight. They literally have paper applications on the plane and have them in hand when you board and exist the plane and you get to hear the same pitch twice a flight too. I will gladly pay extra to fly with a carrier that isn't so shady and dishonest.