How to get a 2013 Ford Focus to rev past 2.5 rpms?

I have a warranty with Ford but they won't fix my transmission unless it goes last 2.5 rpms

Sounds like it is their problem if it won't go past, what is actually, 2500 RPM.

Try putting the shift lever in the lowest gear instead of drive and go on a drive and floor it. If your motor won't go over 2,500 rpm's you may have plugged catalytic converters. I doubt it's a transmission problem.