I have the exact same problem. Also when i try use the support system I get an "updating list" message that is indefinite and I can't use the repair function as it is blacked out and says "Repair can only be used if problems are detected while patching"
It seems like there's no response from the Server side of things.
Just to clear this up, there is 2 patching methods
Letters ST on the lower left of the launcher = streaming mode (bitraider) the repair in the lower left cog will never work, to do a repair is to delete the bitraider folder as per http://www.swtor.com/community/showthread.php?t=729911
No Letters ST on the lower left of the launcher = non streaming (SSN) first you need to be logged into the launcher and just before pressing play , then the repair button in the lower left cog will function.
The DiskCacheArena file is one of the games cachefiles and can be safely deleted when the game isn't running, it auto recreates on the next launch