Stupid warranty

Rewind five years and 2 months. I bought a 2013 mustang GT Premium. Paid an extra $2500 for the 100,000 mile/5 Year warranty. Guess what happened yesterday? My water pump broke. Okay, no biggie, I'll take it to the dealership and get the warranty to handle it because it's still in effect, right?

WRONG! I get a call from the dealership a few minutes ago "okay, so we found the problem, it was the water pump. We are about to replace it. You said you still have warranty, right? Well, it should cover it." I come back a few hours later to pick up my baby with a new water pump installed, go to grab my keys from the service man and he says "that'll be $549". "Uh what? The warranty covers it." I said. He replied "yeah, it would if you had a warranty, it expired a few weeks ago." So, here I am stuck with paying $549 for a fucking part I could have bought from auto zone for less than $100 because some dipshit fucked up and told me it was under warranty.

I paid $2500 for the extra warranty, never needed to use it then got charged $549 to fix a problem that started a few weeks after my warranty expired. I'm so pissed I can't see straight.