Hoian, exchanging Chinese currency

Hi,

Apparently nowhere (official) in Vietnam exchanges RMB. No bank wants it and some have told me to go to certain streets around Hanoi to get it exchanged on the black market. i ended up asking the guy at reception at a hostel i was staying at and he did it for me on the spot for more than the official exchange rate. He told me that the hostels/hotels in Hoian should be able to do it for me too if i needed to exchange more. Now i am in Hoian and i want to exchange some more but the hotel im at doesnt have a clue what to do and banks have told me that they dont want it. Does anyone know where i can exchange Chinese Yuan in Hoian?

cheers