I hate broken links/ non maintained websites.
I hate that verizon fios takes forever to load (WHAT THE FUCK YOU'RE A FUCKING INTERNET COMPANY!)
I can't stand it when, once you do find the email address to request what you want, they never answer... EVER.
I hate the difficulty (sometimes) a company makes it to find their fucking phone number or address.
But hands down the thing that makes me rage the most is having to wait more than 10 mins on hold when trying to contact customer support for any company. (thank GOD NY Gas and Electric put in a call back system because there was one time I was on hold for I shit you not 40 fucking mins).