SCJP exam voucher distribution from oracle and thier validity

I just want to know how oracle distribute voucher to prometric centers.

i called 9 days back to NIIT centers in delhi about OCPJP exam voucher they said they have only 8 voucher so buy it soon (INR 5845\-.).
When i called today again they said they have very limited voucher buy soon ASAP also they said it will be available only till this Saturday after that
i must have to wait for 20-30 days after buy. Then i asked that will i get email on same day i will buy voucher they said no it will come in couple of days.
i also asked for validity of voucher some NIIT center said you will know validity when you will buy it mentioned in voucher, i will get an email.
and some center they said validity is for 3 months for same price, and some said validity will start from the date i buy voucher.

1. so i am little bit confused about how oracle give them(centers) vouchers ?
2. when validity starts of voucher.?
3. In how many days i will get my voucher after purchase.?
4. And how can i know about validity of voucher before buy?

I gave my OCJP last month. I bought the voucher from a NIIT center in Pune. You are supposed to get the voucher by mail on the same day you pay. The validity of the voucher is for a year and the validity period starts from the day you purchase it. I guess the validity of the voucher would be mentioned in the exam admit card which you get by email.