About the payment of pension insurance.

I received papers that pay for pension insurance.
I can choose pay way for these papers.
Pay way have 3 ways below.

1. April 2012 ～ March 2012 every month.
2. each half of a year.
3. a year.

Also, the papers are written that direct debit is cheap than pays.
Further, able to cheap way is that pay one year advance or pay half of one year advance.
However, deadline for pay one year advance is February 2012.
So, payment deadline has already closed.
Also, I thought about get a new job after finished abroad study.
So, I decided to pay direct debit every month.

Papers are written "If already closed payment deadline, then outside scope of direct debit and payment deadline of April 2012 is May 31 2012".
That's mean I should pay April 2012 because now is June 2012.
I don't know how pay it. So, I asked how to pay to pension office.
Then, a person of pension office taught me "You can pay by papers that pay for pension insurance. Also, may be outside scope of pay about May 2012. If outside scope of pay about May 2012, then I will contact you that information."

Anyway, I paid pension insurance of April 2012.
Then, I took procedure direct debit at the bank.