Ay 2019-20, if bank a/c no is not validated at efiling site for a refund case .

I have already submitted an income tax return of a LIC agent with a valid bank account number for AY 2019-20, but that bank account no is not validated at efiling site , aadhar link was successful , from bank side they said that  proper KYC was given for that bank a/c and they assured my client that everything is ok but still account number is not validated at all .

Then What should i do for the above problem ?

Whether validation of a bank account no is mandatory for a refund or not ?

Regards