Shine.com — Payment for document verification

Got a call from shine.com saying about the interview timing and all.. And then got a mail about it... And said it's a paid service.. Asked to pay 3k... Nd said if the candidate will not be selected the amount will be refunded... We have paid the money.. Later, interview has been taken by the company and got the job confirmation mail... They said call latter will be sent.
Now again they are asking to pay 5k for document verification.
Saying it is a core job.. If you don't want then you can quit now but the 3k will not be refunded.