hello all

i just have this instrument for 2 days, it's an olympic white strat from the company called "vintage" - wich i really like.
they usually make very nice instruments for a very small price. this, however is the first strat from them that's giving me a hard time, setting up.

it first had a backbow in the neck, and fiddling around with the truss rod didn't seem to make it any better. i wasn't sure if the truss-rod went the opposite way as any other ones i know of.
then i found out, i have to set the truss rod to where i think it has to be right and wait overnight, to get it adjusting. - then adjust further.
that seemed to work.

now, after this i really did believe that i can go on step after step, as usually do, but i am lost, whatever i do! - the action towards the end of the fretboard is high, you can't play the guitar.
i don't find a way to resolve it.

string height at the nut seems ok (pretty low), checking action with pressing down first fret and last fret (or the one where the neck joins the body) and measuring with a piece of thick paper (from a string-set) just let's it slip under the string without moving it, if i try the same
with a business-card, it moves - that ist usually OK for me.

however, the strings are buzzing, especially around the middle of the neck, as soon i don't play them very carefully. a harder attack doesn't work there.
i can't go lower at the saddle, as the tremolo-block is locked (no upwards bend, just downwards, to tell you what i mean) to the body, and the saddle of the high e-string is almost down to
the term block. (the others are accordingly adjusted, to re-create the "bow" given by the neck.)

if you look at the whole thing, the strings get further and further away from the fretboard,create a very high action at the end of the fretboard, that makes the guitar hard to play if not unplayable.
so, to resume: string height at the nut ist OK (very little), neck relief seems ok, but the action is much too high towards the last frets (up to 21), with no way (to my knowledge) of lowering it at the other end.

what can i do to resolve this?
i never hat this before.
thank you for your advices,

have a nice weekend - miles