Because he is making it up as he goes. Until he produces a fucking invoice from a law firm, he's lying.
And when you hire a lawyer, they get money upfront unless they plan on getting paid from a settlement. So unless he's about to sue Bank of America (he's not), the lawyer would have wanted payment upfront. Phil is lying about getting a bill for $1500. Lawyers 1) don't do the work and hope they get paid (unless there's a well-established relationship) and 2) aren't going to surprise a client with a bill. Both are good ways to not get paid.
Edit: Speaking of the bankruptcy, recall that he had a mystery lump sum of money he needed (like $1800 or so, I think?)--that was the retainer the bankruptcy attorney required to handle his case. UPFRONT.