Earlier Debit Date than Pay Date

Lendplus has helped me numerous times however what I do not understand is when you state on the application that you only get paid at the end of the month that they want to debit your account earlier than the date you get paid. This is even after submitting payslips and bank statements that clearly state you do not get paid on the date they intend to debit your account and then they want to charge you extra because funds are not available on the date they decided on to debit your account. Surely this is *******.