Complain regarding selling a IMEI activated phone by saying a new.

This complain is about a samsung phone which I buy from Jio store. I buy a samsung j7 prime from Jio store ajmer. And I found IMEI number is already activated before 3 months from the date of purchase. And they didn’t inform me about that. The IMEI Number of product is 351678090747625/01 I buy this phone is on 7th august 2018 but IMEI is already activated before 3 months.