scam regarding bak card and access your phone

today I my mother got a call from scammer though it was not showing fraud on trye caller we thought its a genuine call he said he is calling from bank of baroda main branch your old credit card has been stopped working which was actually true and then he said also don't make any payments right now or you online payment app account may get blocked we messaged you but didnt respond to mesaages from the bank and now today is the last day so i will activate it again you will get new card and further you can make payments smoothly we said ok he said us to download any desk app which is remote desktop app I will take control and activate it through your mobile then I caught him it's a scam and we said we will go to bank right now and then there will we talk about this he was insisting no time left it must have to be done by this time otherwise you will lose your money your account will get blocked we cut the call and then figure out it was scam he tried whatsapp calls from other no. as well but we didn't respond no any banks ask control over your phone to activate any account or something.I hope if you get the call something like that you must welcome them with very kind words you know that got pierce in his bumm