Snowy Yetis certainly exist, and they are indeed massive.
Unfortunately, however, they had inherited the complete lack of intelligence of their extended family without a single exception. A Yeti's intellect was remarkably low, much like a Troll's. Wielding heavy clubs and rolling giant snowballs, they attempted to attack the wizards, only to be led around in circles. Worse still, a single Killing Curse from the Dark Lord was enough to dispatch one.
Severus and Snape managed to harvest a considerable amount of fine potion ingredients. Fortunately, the Undetectable Extension Charm bags they brought with them this time were spacious enough, or else these materials could never have been carried away.
Chapter 175