Recently, I got a comment from a Polish native speaker when I used "zbyt" that it was "too bookish" and that in normal conversation only "za" should be used. However, I was under the impression (I read it somewhere in a discussion on Duolingo for sure) that "zbyt" is to be used for "only a little bit off the mark" and "za" for "way beyond"...
That "bookish" thing really seems like their very subjective opinion.
But I am also not aware of that distinction you make here. To me, they're really interchangeable in 99,9% of the cases.
One other note: you wrote "Help me" in Polish and it was correct, but it's not like you asked one particular user for help, right? In most situations such phrases used in a forum will rather be in 2nd person plural (addressed to multiple people that will read it): "Pomóżcie mi" :)