A computing system can receive a primary authorization request corresponding to use of a prepaid payment means of a user of the transaction service for a transaction with a merchant. Based on receiving the primary authorization request, that system can determine that an account balance corresponding to the prepaid payment means comprises inadequate funds to fulfill the transaction. In response, the system can automatically transmit a secondary authorization request to a financial entity associated with an account of the user, and subsequently receive an approval of the secondary authorization request, which enables the system to utilize the account of the user to make up for the inadequate funds of the account balance of the prepaid payment means. Based on receiving the approval, the system can transmit an authorization to the point-of-sale terminal of the merchant to authorize the primary authorization request for the transaction.