Shyness is very often something that has been caused by low self-esteem, which in turn leads to nonexistent self-confidence. And anyone who tells you that "that's just how she is", has no idea of what they're saying. Last time I checked, you could learn things and get better at things, without essentially changing into someone else. The critical part is that the person must be willing to change. If you doesn't want to change, it won't happen.
The thing is, if you understands how nice it is to get rid of shyness, you'll gladly accept the change and work for it. And it's your job to make you see why you should do it.
Good luck!