How can I connect Mobistar satelite dish to free sat?

Hi we have mobistar satelite dish which was connected at our old house. Have now moved and bought dish with us, and have been given a free sat box. Before I get someone to reconnect the dish to mobistar which was not a great service mostly due to badly positioned dish before, I want to know if I can use this dish with the freesat box.
I can not figure if the two are compatible or if I need a different dish. Certainly the fixing are not alike so will at least need some connection changing. anyone done this sucessfully and can offer advice please.