Yeah, there's pretty much nothing you can do.
Buy a new one, trade it, send it to $ony and ask that it be on 3.55 or 3.41 when you get it back, or if it's a phat, ask that it be on 3.15 for otheros. In the past they have done that for people.
Otherwise, there's really nothing you can do.
STOP! Before you ask questions... READ the first post! RTFFP = Read The F*cking First Post
Yes, A 3.55 "jb" (cfw) is available, no >3.55 "jb" or cfw yet.
Yes, A 3.55 downgrade is available. But not to lower than stock firmware! (What it came with)
No >3.55 downgrade is out there yet.