Redmine

We´re running into this situation lately. In some issues, the spent time is greater than estimated time. We need to know how much time is left to finish a version: when spent time is lesser than estimated time, we have a measure of how much time is needed to complete the issue. But when spent time is greater than estimated time, we loss how much time is needed to complete the issue.

How do you advice to approach this situation? I can think of a "Remaining Time" custom field. Some messages in this forums talks about something similar, but none provides a way / plugin to solve it.

Thanks in advance,

P.S.: please tell me if i made myself clear (english is not my primary language)