Membership end dates don't update upon payment failure

[Andrew Cormick-Dockery]

Our administrators are having some difficulty when marking membership payments as "Failed".

Normally when memberships are renewed, the status is automatically updated to "Current" and the end-date is updated accordingly to the length of the membership purchased.

If an administrator goes back and changes the payment to "Failed", the membership is automatically changed to "Expired".  However the end-date of the membership is unchanged.  This leaves the record in a state where the expired membership has an end-date in the future!  The administrators at the moment have to go back and change the end date back to where it was before the membership renewal was attempted, but they're concerned about this manual intervention required.  Clearly it is something easily overlooked by humans leaving records an unreasonable state.

Does anyone have any suggestions as to what should happen here?  Our administrators are requesting a code change to reflect this....