Happened to me 3 times. I called and CSR are no help. A "ticket" was created but they say it'll be 48 hours before they'll email me back. I also wasted 2 hours of my life, so Samsung for giving me and my perfectly working credit card the middle finger.
Not sure if you found your solution yet but I think I solved my problem as the order says accepted now. The problem was with my shipping info. For some reason Samsung's formatting glitched out and made my phone number an invalid number with spaces and missing numbers and so my orders kept getting cancelled. Just be 100% sure that your billing and shipping info are exactly what they should be and you are choosing the right ones. I used the app and had to edit my saved info multiple times for the formatting to finally stop breaking and have accurate info. Hope this helps!