Question about paying a CA

I got a call today and was working on a settlement, we had almost agreed (of course I was going to get it in writing) but he said I couldn't pay by money order or cashiers check. I had to give them or at least write them personal checks and the bonus, I could even post date them.. lol - well I told him there was NO way I was giving him access to my bank account information or post date checks. I then said I would send it my money orders per the agreed settlement. He said something about if I send money orders even though we have a settlement agreement, the money would be applied, but my account wouldn't show in a settled type state and the remaining amount I hadn't paid yet could go to another CA company. Is this just another trick so people make payments and then still get billed for the full amount? And is this even legal?

Anyway, I told him no way. I was not going to make any payment if they didn't show this account was in a settlement state, and if they only applied my funds to the balance but keep it open so this could still be assigned to another CA company.

I would just like to know if this is some sort of trick they use?