Banked my timeshare week against my wishes

Hi<br> During the course of April I made enquiries about exchanging our Beacon Island week 24 room into week 26 because of the holidays as a friend was going to use the room. After a lot of confusion I was told I couldn't swop as I didn't have enough points to move to high season. I accepted this, and wrote to SunSwop to confirm that I was going to make my own rental arrangements. I heard nothing further and assumed that all was in order.<br> Today I contacted Beacon Island to arrange for a guest certificate for the person who is going to be using the room in week 24 as we will be away, only to be told my room has been banked and isn't available!<br> Imagine my shock! I then phoned a few times to speak to Charnell at Interval International SunSwop Administration *** and after a long delay got re-routed to their London office, and a gentleman told me he would get Charnell to call me back. I have subsequently written another two emails asking for the matter to be attended to urgently, but have received no response. I'm going away and this has to be sorted out urgently so I can get the guest certificate for the occupant for that week. Please help - I'm desperate and angry!