Visa problem of my Italian roommate

Im trying to help my roommate. She's Italian. She's worry now about her visa.

Her visa is 3 months, and will be finished Apr 28th. She wants to renew it now. Before, she ordered for tourist visa, then the VN embassy in Italy where she made the visa said that she can renew it in VN. But now, the VN office say: NO, she must come back Italy to renew it!!!

She had a phone number of an agent, I called, and they say if it's C1, 155$ for 3 months. Then I checked her visa, hic hic, my Italian has known that her visa isn't C1 just after almost 3months here, isn't for tourist as she ordered in Italy, it's B3, for working.    This agent doesn't know about B3

Now the problems are:
1. VN embassy made mistake, but how can she do to prove it and order them to fix it?
2. it's B3, ok, how can she do to renew for 3 months in VN? She works in a pagoda like a volunteer w/o salary or contract, it's not really a job and helpful for visa? 
3. If she can renew here, how much?

Wait for any advice, tks a lot!