Bonitas conducting questionable business practice.

This year my Father had to have a neck operation. They advised him that he had to go onto a higher and more expensive plan to do this. Being pensioners they could not really afford this but he had no choice. They changed plans in June to a higher plan. Now they got an account from Bonitas for R6000 because when they went over to the higher plan, they had already depleted their day to day funds for the year. Please note that they did NOT go to another medical scheme, merely a higher paying plan. They have paid for their day to day out of pocket for the last few months. If they had gone to another medical aid, I would understand them owing Bonitas for the remainder of the year but this is not the case. They should just not have day to day for the rest of the year. My question is also, if Bonitas sees another plan as a new start, where is their "new" day to day benefit.