How can we improve WHMCS?

Sometimes it is necessary to apply account credits to multiple customers in one batch - i.e. everyone on a specific server. The credits usually take the form of a percentage of their monthly subscription charge and are applied in cases where I have failed to meet my service level guarantee due to server issues.

It would be very helpful to be able to filter all clients residing on a specific server, or under a specific product, and then be able to apply an account credit en masse... either in the form of an automatically calculated percentage of their subscription, or even just a fixed amount.