uco bank ke regarding fraud

my father is a farmer and so there is call from bank manager in WhatsApp that your life certificate is not approved so we need you to done ka kyc and then the refer a app of uco bank and then they fill the application form but they don't share there pin and any other otp but they got scammed of 83500 rupees and worst part is that in there account only have 13500 so the scammer first credited 70000 from his joint account to single account and then the scammer purchase some vehicle in 49500 and 34000 rupees now how can we get the amount from them because they purchased something not credited to their account