Allow a negative balance on revolving credit accounts.
More and more customers use revolving credit products with a high volume of transactions in credit-card-like products. This increases the chances of a transaction refund being required. In case the balance on the revolving credit account is less than the refund, the refund cannot be processed as it would push the account into negative balance, which is not allowed.
This makes for an inconsistent user experience as the refund either cannot be processed or would need to be posted to another account e.g. transaction account.
Also see this comment on DPS-23 in relation to this idea.