We sincerely apologise, we had some serious issues with the last build.
If anyone purchased Arcade mode and is being asked to buy it again please use the Restore Purchases button we've just added. In testing it sometimes took a few tries to successfully restore, but I believe this has to do with waiting till Google Play has responded that it is ready to purchase. Playing a round of Classic mode will probably give it enough time to set itself up and should then work the first time.
Have fun with the free credits and jump over to our Facebook page and tell us which Perk you like the most, or even make some suggestions for new ones.