society maintenance charges

One of member of my society is owning 2 flats (1 BHK & 1 RK). But he has registered them as 1 single flat. He was the chairman earlier, so he designed the maintenance payment structure in such a way that he has to pay maintenance for single flat. But with the reconstitution of society trustees, it is been decided in general body meeting that he has to pay maintenance as per flat unit ie. maintenance for 2 flat. As there are many members who stay in 1 RK, but they are paying maintenance as per flat unit. But this person is staying in 2 flats, but paying maintenance only for 1 flat. He refuses to pay maintenance for 2 flats. Please advise the course of action to be taken.