Pay into mortgage

My husband and I want to pay straight into our mortgage, we will be paying the mortgage plus about 400 pm off arrears - our own choice. Can this be done ? Iwas told No by Ulster Bank yet my tennants in my other house pay direct into the mortgage ? Why cant we do the same ??

Different computer systems, some are set up like that, others not. You can usually increase your direct debit by agreement with UB if it is a fixed amount you want to lodge each month.