What I need is shared hosting with different C-class IPs
IP Classing STOPPED in 1995.then you don't need to worry about the C Class IP that you're hosted on.
What level of customer/ technical support do they offer? Online only? Phone? Email? Etc.?As long as you choose what seems to be a reputable hosting service, then you don't need to worry about the C Class IP that you're hosted on. I would recommend you to choose hostgator, siteground or inmotion (http://www.sitegroundwebhostingreviews.com/siteground-vs-inmotion-hosting/) that are perfectly fine choices.
Your C Class IP will only affect you if very shady/spammy site's are hosted alongside yours. Even then, we do not know how significant of an impact it has.