In the shop, use Wipe Stamps to clear the unlock from a card in your deck, (locked cards must be unlocked in the main play scene) that allows you to put on one of the other two stamps. Swap, and Wild.
Wild cards (W) work as a connecting card to the nearest, largest straight, if possible.
Swap (Circle of arrows) allows you to Click on that card, and then another card +2/-2 from its location to move it around your hand. Use this to reorder cards and set up straights.
As for 13 v 8 Wipe Stamps...not sure? stamps are consumed on use so maybe you've used 5? Otherwise that might be a bug.