They literally let you roll around in the gacha (haha see what I did there?). You can do the whole DMM Step-up Gacha for 10 bucks, with 2 Five stars guaranteed...
I had no trouble with my Visa card, so I don't know what's up with yours.
ALSO, THEY MAKE FACES WHEN YOU CLICK ON THEM IN THE HOME SCREEN NOW
And look at that raid boss count, dear god. No wonder they get 6 raid points instead of 3.