Hi Sololssy
I will never ceased to be surprised how incompetent airlines agents/call centers can be sometimes, even on the most basic situations like yours. I am 99% sure you won't have to collect your bags in SGN.
Can I ask you the question (just for my curiosity) : did you buy this ticket to EK directly or through a 3rd party (travel agent including on-line ones like Expedia) ?