回複：When lawyer-client relationship goes bad what should I do?

If you signed the contract and he/she filed your application then you are obliged to pay whatever stated in the contact.

I had a similar situation (but the fees was much less) and paid in full because I do not want to have any trouble before I receive a GC. I believe you do not want to either.

Try to argue to pay less and keep the records (e.g. email), that may be a better solution for you if it works.