Our professional and premium plans also include priority support. At any time your engineers can escalate an issue or discussion group thread, and we'll ensure it gets a guaranteed response within the next working day.
The ticketing system is fairly informal, just raise an issue on the issue tracker or a usage question on the discussion group.
If any of your engineers email me and request that it gets priority support then I'll make sure it's the very next thing that gets my attention.
We could implement something more formalised if needed, but this has worked well enough for our sponsors so far.
Hope that helps, let me know if you've any other queries!
Tom