I can tell u the steps:
1. Unistall/delete Fifa than completly new install all
2. Do this 5 times
3. enter 3? times a wrong security answer in web app (as often as u can) make sure that u have cleared your browser cache
4. contact the EA live chat and tell them that u forgot your security answer
5. the live chat have to "activate" your account to give you a new security answer
6. than following the steps from the support person and enjoy.