Ace 2 Phone Screwed

[Aerofly]

Been using my Ace 2 for the last 12 months using the Gingerbread software without any major problems, the other day when I connected to the dreaded to back-up my contact list I noticed there was an update to Jellybean 4.1.2 so I upgraded, I now have a problem in that all my contacts are joined and the phone will not let me make outgoing calls although incoming is not affected, does anyone know how I can un-join them?, I have tried deleting my contact list and entering manually but they are still joined, if not how do I get my phone back to Gingerbread OS.