As some one stated bad publicity for a Uni isn't fun.
NO MATTER WHAT ALWAYS MAKE YOURSELF LOOK GOOD. make the letter seem concerned and helpful and well-intended. Try not to throw words or make any accusations. Stay as neutral as you can with wanting to help the snake as your only goal. I say skip talking to the woman again and go to the head of the bio dept or the dean. if no one is willing to listen call the college's paper or the city/town paper (depending on if the school has one and or the town/city paper is small enough to be seen by some of the public ie front page- that would make front page here i mean, the bio dept not taking care of an animal? duh.)
it has always been hard for me in confrontation to make myself look 'good' and not get hot headed or over anxious when i know some people are wrong so please dont make my mistakes. if you appear as a kind, concerned person that simply wants an animal to be taken care of and not an 'evil nazi snake freak' as lol i would come off as im sure you'll definatly light a fire under something.