sprint cap on hotspot Internet

I have been with Sprint for over 15 years. 5 years ago i bought a wireless hotspot card for my laptop i use for work, home, and travel. I had a seperate contract and had unlimited service. When that broke and I went to replace it I was told I would be beter off getting a new phone and add it to my plan. then I would be able to run 10 devices instead of 1 for the same price. So i upgraded my flip phone for a evo and added the hotspot and loved it. they made me sign a 2 year contract witch I did not have for 5 years. Last month after only having the hotspot for 14 months I get 3 email warnings that i was about to go over my 5 gig limit. So i called sprint and they told me it is a add on and My conract dosn't include add ons that i will be charged extra if i go over. I think that is wrong and they should be investegated for this. They should give us back unlimited and new people that sign up can be charged for 5 gigs i bet not a lot of people would sign up.