Keep filling the Piggy Bank until you see a message stating ‘Piggy Bank available. ‘ Then simply choose whether to unlock it there and then by paying the stated amount, or keep on collecting until you get the ‘Piggy Bank full‘ message and then pay to unlock it.
in fact, What are coins used for in bubble pop?
Coins are used to purchase boosters to help you in the game.
for instance,
indeed
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