Management company sink fund

Morning all I'm having a blank moment! Management Company no 2 charges a fixed service charge per flat. Has made a profit in 2010 but would like to use the profit to put toward a 'sink fund' for unexpected/exceptional repairs and maintainence for the buildings. I would credit the sink fund but as they charge a fixed fee to each flat can I debit turnover?

I have another management company client, no 1, who's service charge changes each year to cover cost, so any 'profit' made is simply split between each tenant and credited to their account and therefore turnover adjusted for the year. As management company no 2 have always charged a fixed fee I wasn't sure we could change it to fit in line with management company no 1. Hope that make sense.