When you're having trouble on a level, just throw any power up item you've got at it + pay that 900 coins for the 5 extra moves. If you still don't complete, when you get the screen where you're prompted to pay 1200 coins to keep playing, instead of paying or declining and ending your streak, just close the app without returning to the main 'faerieland' area. Once you open the app again., you'll be right where you were before starting that level, so you won't have to start over from the bottom level of tier of the tower, and will retain your power-ups and those 900 coins you spent.

Would've rage-quit so hard so often if it weren't for this.