I need an immigration lawyer

I have a biological son in Brazil to whom I wish to transmit US citizenship. The US consulate insists that he and his mother fly over 2,000 miles to provide a DNA sample, and for the first appointment, they only gave us two days' notice to make the trip. Since then, they've been unwilling to schedule another appointment. I've already tested positive on two paternity tests and paid $550 for the USCIS test. I was wondering if you could help me with this case and how much it would cost?