I wrote a thread about this on super premium cards group i think a while back. Please cancel if possible, it was such a horrible experience.
Get ready to be bombarded with sales pitch for 15000 USD throughout trip, and if you say "leave me alone", they will treat you like dirt. Only option is to put up with it for 2 nights and get like few hours of privacy in a day because they will be there in the restaurant too.
Booked through same HDFC 3 page stupid PDF which does not warn anything about this. Also once u land in vietnam airport, you can actually see stalls of them which offers exactly same deal, HDFC is not doing any favour. You could be a nobody and still get the same deal unfortunately