I've been a reseller for most of the decade and I can honestly say in all the times we've called, we have never had a single issue corrected by support. We usually end up having to find workarounds for bugs. The last time was an autosuspension our panel(s - there are two versions now) would not let us un-suspend the client. This left him without email for a week, while support would only respond during the early AM hours, and would repeatedly ask us to prove identity, even though we were registered resellers with admin panel access.
In all the years of working with different vendors, I honestly cannot think of a single one with a 0% success rate in their support.