does all seller basically sell the same HDTV version? is it stable lately?

last time i bought HDTV from a seller at lelong on January and used it on the new STB, always got delay and voice-lag..sometimes some channel wont even load..damn annoying...video resolution/screen ratio also so far off, cannot configure...can only see half of the subtitles below..

only subscribe for a month..seller only told me to reset my STB n router but it's only a temp workaround..will have delay soon after change to several channels..very annoying have to reset everytime wanna watch..