With card transactions, first there is a pre-authorization by the card issuer which temporarily puts the amount of the transaction on hold, then there is a settlement. If things go wrong during the processing of this transaction, the merchant may not send a settlement and instead send an authorization cancellation.
Typically in such cases, we get a notification that can take from a few hours and up to 7 days letting us know that the transaction is cancelled. Once we get notified, the funds are applied back to your account.
If this has not happened contact us via the Settings section of the MuchBetter app.