Looks like it is retained by Phillips headed screws that go directly into the heatsink extrusion itself, should be simle enough to remove, althouh you may need to take the plastic cover off to release the fans power lead.
First off, contact your supplier, it's probably still under warranty, although you have to go directly to XFX themselves.
Second option is to contact XFX and see if a new fan can be obtained through them.
Final option is to find a case fan of about the same (or slightly larger) size and use self adhesive Velcro pads to stick it to the case, either as a stop-gap until XFX can supply a new fan or as a direct replacement.
It's a good idead to remove the old fan BTW, two sets of blades operating close together can make a lot of noise and if the old fan jams it's going to restrict airflow.