Make sure that you have clear evidence of the paraphrasing done by the writer. Screenshot the original essay and submit that as evidence once you file your complaint and demand for a refund. If you have not paid for the full paper yet, then do not proceed with the final payment. They definitely betrayed your trust and confidence in this case. The best thing you can do for yourself is file for a full refund and hope you get it as I am sure they have a refund guarantee for the academic papers, specially those that can be proven to be plaigiarized.
As you deal with them, make sure to come back here and start a new thread. Tell us your story. Make sure to indicate the company name and writer identity (if available) to serve as a warning to future students who may wish to procure their services. Making the issue public often results in the company becoming more cooperative towards refunds. Do these simultaneously. That way the company will know you mean business when it comes to your refund demand.
You may also post the original essay and the paraphrased on when you post here to serve as hard evidence of their criminal act. The only way you can deal with them is to try and do damage to their reputation. You can do that only by going public with what happened to you when you used this company.
The opinions are that of the author's alone based on an individual capacity. Opinions are provided "as is" and are not error-free.