How wrong is this?

I work for Walgreens Corporate. Ive been working for them for over three years. I have gotten 3 miniscule raises since I first started, and up until last week , I make 11.95 an hour.

11.95 per hour. Ridiculous. Anyway.

I received my company e-mail stating they are raising their hourly wages to 15.00 an hour. At this point, I am thrilled. Its better than 11.95. Much better. Im thinking at this point that I would like to end my search for another job.

Then, my supervisor calls me with the "good news".

My rate has went up to 12.50 per hour!

A .55 cent raise? After being told I was about to get 15.00?

I asked my supervisor, why only 12.50? She says " well, employee who have been here over 3 MONTHS goes up to 12.50."

I. Have.been.here.for.over.three.YEARS.

By the way, NEW employees start out at the full 15.00 from here on out. So i have to sit there and watch new people make more than me.

Should I pack my things and go?