Novice to VBA/Macros & indeed to Excel in general!

I am generating a tracking sheet with the help of the members of this forum! The last issue to resolve is that I need it to be able to flag up if calls are not being dealt with in the correct timeframe. This involves calculating differences in terms of hours & days.

C3 logs the time the call came in
S3 logs the time the call was allocated to an engineerService Calls Tracking Report.xlsm
T3 should calculate the difference in time between C3 and S3 and display it in hours (under 24hours) and days (over 24hours) - it does not currently do this
M3 gives the call a priority as a drop down menu (1, 2, 3 and When That Way) - these are colour coded
N3 assigns a maximum timeframe to the priority according to what is selected on M3 (4hours, 8hours, 24hours and 7days) - although I don't think this is formatted correctly

I want T3 to go red if the timeframe has exceeded that denoted by the priority.

Hopefully that makes sense!!

Service Calls Tracking Report F.xlsm

Thanks

Fran