Main problem was:
1. If you didn't click on the special link from U2.com OR you were on Mobile, Red Zone NEVER POPPED UP. Simply going to ticketmaster.com and clicking on their link (which should be entirely VALID, because it says it should) DID NOT WORK.
2. RedZone DID NOT REQUIRE A PRESALE PASSWORD
That is what people are upset about. If you managed to get a RZ at London good for you. You lucked out, don't tell us however not to be a tad miffed.