My personal experience is that there is a significant difference in the level (and quality) of support received between regular production support and business critical support. I have always received responses (on all cases), but the level of technical expertise and quality of service is noticeably different with a business critical support contract!
Hope you get your issues resolved soon 
Cheers,
Jon
vExpert 2014 - 2022 | VCP6-DCV | http://www.jonmunday.net | @JonMunday77