Time based alerts or tasks on business days

Time based alerts or tasks on business days

I have set up a work flow rule, in this work flow rule there is one alert and one task. This rule is activated in the event of an updated field. The rule works great and has a time based alert and task. These work perfectly. The problem I have is that I require the time based calculation of 5 days to be 5 business days. Currently I can only get 5 calendar days to be counted.

I have adjusted the organisations working hours and my calendar work week details.

Is there some thing else that needs to be used to have the due date of the alert and task to be calculated on business days.

Any advise or recommendations would be awesome.