If your pet has only one ability called Rot Armor, has about 11000 health and is not elite, it is not right.
Your pet must have 3 abilities, have about 53000 health and must be elite. In the first case, Relogging is a must.
Also use a lvl 76 pet instead of 75 pet. Lvl 76 pet is slightly stronger.
I find this quite difficult considering my disguise disappears every time I engage, and the pet disappears with my disguise. The pet is not strong enough to win the battle. So the draw aggro first does not work. Best to have your pet damage increased, then go in with the stun, follow with gut rip, and continue until damage increase is available and hit it again. This does the trick and yes use a lvl 76 servant.