how to remove drivers side heater vent

[stevemcintyre85]

Hi I've got a 2007 A4 convertible and the drivers side heater dash vent is broken, its the chrome circular style ones , i want to replace it but not sure how to get it out! had a good last night with some small screwdrivers trying to leaver it out over some(if it indeed has) clips, just wanted to know the best way or if i need to look for screws or hidden clips.

thanks in advance