Read through the vertical service codes here http://www.nanpa.com/number_resource_info/vsc_definitions.html to see if any can help your situation. Searching for "call forward" on that webpage will lead you to the VSCs that affect call forwarding on your phone. I would try deactivating everything that has anything to do with call forwarding -- *91, *93, *83, *73, and *88. I hope you read this. I've bookmarked this page and will come back to see how you fared.
BTW, I've read that criminals sometimes perform a DDOS on your communications (phone, email, whatever) when they steal from your bank accounts (transfer funds from your accounts to criminals' accounts) so I suggest you check your bank accounts frequently until you regain control of your comm channels.