Go to this site http://www.marsballsgetbritainplaying.com/bounce/
( Clicky in next post )
If asked, enter your date of birth.
Then click the "No Purchase Necessary" button to get a code.
You are allowed 1 code per e-mail address per day.
Then just keep entering the same code over and over again until you win.
The later in the day/night you enter it seems it becomes easier/quicker to win.
They don't seem to spam the e-mail addresses.
For those lazy people out there, you can go to this thread from here and enter a macro to do the entering for you.
This might not be everyones cup of tea though.http://www.hotukdeals.com/item/441630/mars-balls-get-britain-playing-how-/
( Again, clicky in next post. )
THIS OFFER RUNS OUT ON 31st AUGUST.