Before a week a sales woman called me from Citi bank to offer their credit cards.
I was interested & accepted to get more information, but she asked my personal mobile number to communicate and send me the details through whatsapp.  

Honestly I didn’t expect that but I gave my other mobile number and she directly started chatting with me in whatsapp.
She sent me the details of all their credit cards and requested my cpr number and copies of bank statement to check my eligibility. I don’t know since when whatsapp became a formal tool of communication for the banks but I'll give them rating 1 because of their unprofessional manner