I was in the same position about 3 months ago. They promised that they would increase my salary because they acknowledge that I'm extremely underpaid. This was suppose to happen in July. July came and gone and nothing happened. I asked if it's going to happen and they said no sorry but their budget doesn't allow it and that they will try to increase it in December. They also said that if I do decide to look for another job, that I must inform them and then they will fight for me to stay here (counter offer). So guess what, I started looking for a new job, and I got a very very good offer, I informed them, and then they said but there is nothing they can do to keep me here. (which I'm actually glad for right now).

So I'm starting my new job the 20th and looking VERY forward to. I'm even counting down the days till when I start working there! Not only am I basically going to get 60% more at my new job, but it's a new opportunity and new challenges. So instead of me hanging around here for another 3 months hoping that they will give me my increase (which I doubt would've happened), I will get paid 60% more end of next month! I've been at my current company for 4 years now and I dread coming to work every day. Also did not want to leave at first, but now I can't wait.

So my advice, look for a new job, and get on with your life. There is alot of exciting opportunities out there. Just need to find it. Don't sit around waiting for something to happen.