Response-time targets aren't confirmed yet, so this page doesn't list any. Here's how requests are handled today.
Awesome Cause answers every request for the sites we host.
Hosting alerts come to us, not to you.
VIP Maintenance clients are in a priority queue, ahead of hosting-only email support.
Responding and fixing are different
Acknowledging an issue isn't the same as resolving it. When targets are set, you'll get one for each.