Omg!! One more similar story. I know how horrifying that experience would be.
I can feel it because I experienced the same. Refer the link below.
https://www.beatthegmat.com/710-gmatprep ... 93586.html

I think you need to analyse your performance in the official test as well as your preparation before booking the next date.The information provided by you seems to be meagre to analyse on what could have gone wrong on your D-Day?
My questions:
What are your scores in last 1 month? in Which Tests? with Quant+verbal break up?
Did you take repeated tests?
Were you tired and lost concentration on official test day or did any blunders which you dint do in your other practice tests?
Did you guess a few last questions in a row marking same answers?

During last days of prepration i took 2 MGMATs n 2 GMAT prep tests

MGMAT 1[/b] 670 (maths :49 ,verbal : 34)
MGMAT 2 650 (maths :48 ,verbal :33)
GMAT Prep 1 660 (maths :47 ,verbal :36)
GMAT Prep 2 670 (maths: 48 ,verbal :37)

i did a lot of practice questions and especialy SC was good ,but today while giving test i felt that
the standard was way above what i had practiced ......
Actually i dont wanna do OGs etc again cause after doing the ques again and again you get familiar with answers etc ......
So please suggest some good tests or 700-800 level or tough quesion sets
for verbal esp :/

Megs17 wrote:During last days of prepration i took 2 MGMATs n 2 GMAT prep tests

MGMAT 1[/b] 670 (maths :49 ,verbal : 34)
MGMAT 2 650 (maths :48 ,verbal :33)
GMAT Prep 1 660 (maths :47 ,verbal :36)
GMAT Prep 2 670 (maths: 48 ,verbal :37)

You did well in your practise tests. But again your actual score is offset by 150 pts Appx just as in my case. Why do you think yor official score differed that much? It is very important for you to find out answers to that question for yourself. Otherwise it could well happen that you score 750 in your practise test and score a 600 in your second attempt. I am not trying to discourage you friend. I am in exactly same phase as you. I am planning to retake in 1st week of Jan too.

Megs17 wrote:So please suggest some good tests or 700-800 level or tough quesion sets
for verbal esp :/

Well If you are looking for tough tests, then I would say go for Kaplan Tests.
Kaplan verbal is tougher than any other tests I have taken so far. However there a buzz that Kaplan does not give right scores/algo is flawed etc. Dont take scores too seriously rather improve your weak areas(the things went wrong in your official test-1)

You can also refer to these materials if you want some tough verbal stuff.
1)LSAT CR questions
2)LSAT RC
3)RC99
4)Brutal SC(It is filled with a few controversial questions)
5)Kaplan 800

I have them all. I solved a few materials from them. They are all really good. Incase you couldn't find them in google or anywhere, just let me know, I will e-mail them all.

Before solving them all, I would really suggest you take a 1 week break and explore/analyse what went wrong in your official test.