Hi there and welcome to Just Answer. I'm sorry to hear about your camera. I will try and give you an accurate and precise answer.
When you say that the lens 'opened up' can you tell me what you mean? Please be detailed, remember that you are my eyes and ears so the more info you can give me, the more likely I will be able to help you in return.
I would send it to United Camera. Here: http://www.unitedcamera.com/canon-ef-s-17-85mm-f/4-5.6-is-usm/#ShowSelections
I am in no way affiliated with them but have used them twice with success.
You are probably looking at a repair in the $90 range. Give them a call: XXX XXX XXXX
I would not try to repair it yourself.
I'll be here if you need more help.
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UC will repair it to spec (if it can be repaired). If they can't, they won't charge you and you will just be out shipping..
They are pretty good. They are the only people I would send my 300S to.