Sony Xperia Go JB Update

hi, i recently updated my "sony xperia go" to the new "jellybean" update, and since then i have had horrible problems with the phone:freezing when i try to ring, or receive phonecalls and randomly just turning off.

now i have had a look around various blogs and it seems to be a huge problem, but there is no real way to fix it as of yet. Its very frustrating as i am missing out on important calls so i need it fixed asap.

I seen a lady say she got her phone flashed by a third party "jellybean" update and now her phone works perfectly. i never got the chance to ask about it but i am just curious if anyone would have information on roughly what she had done to get the phone fixed?? thanks