I would say that's a question that you have to ask the provider. We don't know where you got the phone or from whom. Give them a call and ask them.
I just bought a phone today and got the 40$ plan but want to upgrade to unlimited data. Do I just pay 20$ more?
The thing is they will do the same thing to u they do to me. They slowwwwww down the speed then u want to throw your phone at that salesperson