Note: If the app crashes, ignore as the items will automatically go into your inventory.
If you use this too much at an early level, the game save will become corrupt. My advice would be to use this every now and again and not too many times at once.
Problems also seem to occur when buying a lot of the event crates instead of the normal ones.
For those having trouble with starting a new game, try this:
gameCenter→sign out
Application→uninstall
application install→From the beginning
gameCenter signin→account stop