Airtel — about flat 50% percent cashback offer

Address: Dakshina Kannada, Karnataka, 574203

It is given that, there will be flat 50% cashback on recharge through airtel payment bank.so i recharged for 448 and i got only 20rs and when i called customer care there were telling that you should recharge 5 times to get 50% cash back.so
Now the point is the given information about offer is wrong so i need full cashback and i dont want any offer from your side.