Did you post this on the mage forum or something? Cause I'm not too sure how you'll get someone here to fix something about class balance.
I hate rogues. But I also don't pvp very often and consider myself a noob.
The key to rogues though is staying on your toes, trying to always be one step ahead of him, and modifying your play style to accommodate what they bring to the table. Mana/Ice shields, instant cast spells ( <3 PoM), and rank 1 AE and Blizzard are your friends. Try to get a DOT up on the rogue (through fireball or something) to prevent them from going stealthed. When you frost nova, strafe to the left or right, that way you only have to do a quarter turn (if that) to face them to cast again. Using the mouse is faster to turn than the keyboard, as well. When using your instant cast spells, remember that the rogue will keep wanted to get behind you - so you have to dance like a rogue and keep trying to stay in front of them.
Good luck.