Thank you very much for information! So far i think i will try only to exchange. Until i find representative in VN.
As for your request - hardly i can help much
because i do not collect FDC and anything like maxi card. I only collect stamps. And i do not deal with a people who sell FDC or something like this here.
I think i have some Olympic stamps if you interested and barely have any stamps with Vietnam on foreign stamps (except few russian).