Hello! I have recently bought carrier360 silver package for neet for rupees300 for payment through phone they asked my atm card no. Pin cvv

No your bank account may be compromised. Though careers 360 is trusted, they can't assure that each of the employee in there are good. There are many cases nowadays that a organisation's employee did some manipulation with sensitive information of users. I don't trust even Flipkart. No private organisation, company is trustable when it comes to money. For their benefit, they can do anything.

Dear Tanzil
It's okay.  Don't need to tensed. As you're in a young age and you don't have any experience in this thing.. You might felt that.  But Careers360 is trusted website.  So no need to worry about that.
All the best.