For those of us that had presale issues and had contacted U2.com via the form, I just received this email:
Dear U2.com Subscriber,
We understand you had difficulty securing tickets in the presales last week for the band’s 2018 shows.
We’re pleased to tell you that Live Nation have announced second shows in many cities on their North American tour.
We will be inviting you to take part in the opening day of presales for these shows next week and we will email you with details nearer the time.
best wishes
The U2.com Team
I think there's should be some kind of refunds if there were loads of issues with this.