I doubt there is much IT knowledge on most "help lines" and that support will usually be limited to a very limited number of devices and circumstances.

One I noticed the other day concerned VPN, which I wouldn't have thought too uncommon a requirement these days... I'd noticed my own (outside to my router) was broken and started to look at the Plusnet support. What I found there was that there were users (although going the other way, eg. like a home worker to an office server) who had problems in the past and that l2tp/ipsec was broken on some IP ranges (seemed like they were moving people around). But the telephone help lines did not support questions about VPN...

(was able to fix mine btw as a firmware upgrade for the router offered ipsec/xauth which did work)