November last year I got mine. I used an agency in Samui for my bounce and was very efficient. All depends where u live in Thailand I guess! Why did they only give you 5 day stamp for Vietnam? I got like 30 days I believe
Mine took approx 5 days from Hanoi embassy and arrived the day after I got back to Thailand. I then did a border bounce to activate the visa. Not the ideal method but it is possible. Can you not change your return flight?