Is there a place to report a provider who accepted a deposit then ripped me off?

wow, not thinked such things even possibly.

And you got ripped off? Tell us more…

First, you can post with more details to your Regional Discussion Board. Where are you, Boston? Search the Boston board for "ripoff" and you'll see some examples, e.g.,  
http://www.theeroticreview.com/discussion-boards/boston-9/emma-kay---savannah-marie-ripoff-ter-id-273015-review-provider-223870
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You can also write a review. TER does allow Ripoff reviews. The example above (Savannah Marie) is one such case. She has an all caps red "RIPOFF!" under her name! (Sad. I remember when was an RSG girl.)  
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You can search for more Ripoff Review examples by doing a review search with just one filter:
"Overall Performance"
[ 1 - A total ripoff ] to [ 1 - A total ripoff ]
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Thanks for helping us all out with whatever warning you can post.

Put one for rip off .  Please do share!