Protekt® Aire 5000DX Cover for Low Air Loss/Alternating Pressure Mattress System by Proactive Medical

I ordered through shop for a price of $221.00 and they charged my card for the first payment of $55 and I signed all the paperwork for the loan agreement for three more payments of $55. I never got a confirmation so I called spoke to a man and sells he said he was going to check on what was going on and I never heard back from him. Then I received an email that there was a price increase of $64 that they were just notified about and I would have to pay that in order to get it shipped. I could totally understand if I was told before they charged my card and I didn't sign the loan agreement through shop but I already had a receipt and they charge my car and it forward me that they wouldn't honor the agreement and ship the mattress and instead wanted me to pay 64 more dollars. How can you have a receipt and loan agreement and card charged then be told you have to pay $64 for a increase that they just found out about.