It's been 4 days and no response on System impaired case

I have a Developer Support plan, they claim to provide support within 12 hour for a System impaired case but it's been 4 days and got no response no one is yet assigned to my ticket. I did also created another case but still no awnser. This is so disappointing. I can't use the service properly which causing me to delay a presentation for the top management of our company. Unfortunately it seems that they doesn't care about their customers at all. My cases IDs are: 14104750401 14131045311