Epic battle to change debit order date !!

Phoned customer care today, to arrange for my debit order date to moved to the 5th of each month. I explained to them that my salary will only be available in my account then, and not on the 1st of every month anymore.

They said that the closest available date for debits apart from the 1st will be the 10th. I was then informed that they will debit my account on the 1st and 10th on the first month, to be a month ahead. The more I explained I wont have money available on the 1st, the more the were adamant. When asked why both dates need to debited, they again said that's how they work when debit dates are changed. Not everyone has the money available to able to afford 2 debit orders per month.

How am I suppose to pay 2 debit orders per month, when I cant afford it. When I try to change the debit order date, they came up with this, seems they just don't want to help their customers. Seeing there wont be any money available on the 1st, and they do not want to accommodate clients, what else am I to do ? Transfer the money each month after they tried to debit it ?

I'm sorry, but this is utterly unprofessional from them. Totally disgusted by how they "want" a debit date change to be done. Seems I will have to find another medical aid, and discourage people from signing up with Discovery Health ?