Do I need to have the Lawyer's G-28 sent in with the Petition to Remove Conditions? Would I still be able to seek representation later on in case they send an RFE in case I choose to submit it without it?

We were investigated by DHS this last June and at that time I was referred to an Attorney who took my $3500 retainer and he has literally done nothing on my behalf. Now that I am submitting my I-751 application he again did not even give me a print out of the forms I needed to fill out, yet he just wanted me to bring in the complete application so he could add his G-28 as a reason charge me more money.

Two years ago, we successfully submitted the original petition without representation and I'm confident about my I-751 as well. I am considering submitting the application without showing it to the Attorney. My undestanding is that it would only state in writing that I'm being represented by him and that any communication would be going through him.. . but wouldn't really affect the adjudication process either way. Correct?