Woolworths pesto contains Animal Rennet

While I am an avid woolworths shopper and love the brand, I am highly disappointed! While cooking a meal I got pesto for the first time from woolworths instead of my usual place and was horrified when I read the bottle and saw it has animal rennet in it, this is derived from lamb,calves and goats stomachs. I am trying to follow a more vegetarian lifestyle and find this is absolutely aweful, I am writing on hello peter to make vegetarians aware of this aweful issue! How can they do this ? Alot of vegetarians use pesto. Very disappointing!