If you would be so kind as to post a few sentences where you think 'will' may or may not be correct, (then) it would be helpful.
If you will persist in making all that noise, (then) I will have no alternative but to ...
In addition to DavidL's example, where it is used to show that someone's behaviour is obstinate, persistent, etc, it can be used when negotiating with someone:
If you will stay late tonight, I will do it tomorrow.
(It balances and makes both sides equal)