Are you saying that because you tried it and it didnt work? Doing this has helped a lot of people with this issue. It is even suggested on the dev team blog.
If you are on the ipad baseband already you can try installing a older version of ultrasnow to see if that helps, if not then I am not sure what you can do. Hopefully the new method of dowgrading the baseband that the dev team is working on will help you.
I own an iPhone 4 and this is iPhone 3GS so micro sim wont fit and since wi-fi is greyed out I cannot downloading anything so for now my hope is wait for the downgrade and then upgrade again to 06.15 hoping this thing wont happen again
Well if they get the downgrade working you may not need to update to 6.15.00 again. You may be able to downgrade to a normal baseband that can be unlocked.