The block period was discontinue by ICAI , but later they extended it to 2013, there was a fix hours seminar needed to be attend in a block of 3 years, but now the CPE hours are needed to be attend every year for at least 22 hours in a whole year.
There are many study circles which organise CPE seminars, the schedule of CPE hours are fix by ICAI, you can attend any seminar as per ur choice, but keep in mind 22 hours.
The different study circle charge different fees for a seminar, they also offer u a annual membership in one payment, and u ca attend all seminars in that year, or u can pay for a single seminar.