Rear brake cailpers won't collapse on 2007 ford fusion

SOURCE: No transmission fluid Dipstick on my 2007 Ford Fusion

depending on which trans it is there is a small dipstick on the trans at the front on the bottom these transmissions take a specific fluid so be careful

SOURCE: cant get rear caliper piston to collapse 06

The rear calipers on that model rotate in, it requires a special tool.

If you pushed too hard directly in, there is a chance that you may have damaged the caliper.

SOURCE: Replacing rear brakes and Rotors on a 2006 Ford

you need a piston return tool to push the piston back in also remove the brake cylinder cap

SOURCE: REPLACING BRAKE PADS ON REAR

use a c clamp

SOURCE: how do you press the brake caliper piston back on 2008

First, take a look at the piston, if it's flat or cup shaped, put an old pad at the piston and use channel locks to squeeze it back in, opening the tool wide to get it to catch the back of the caliper.
If....the piston has what looks like an "X" or cut outs, this is for a tool that spins the piston in with a special tool. (Subaru's and some other cars use this)
After you are all done and pump up the brakes, re-check the brake fluid level.