My question involves collection proceedings in the State of: California

I was in the process of negotiating a settlement on a judgment with the third-party collector (a lawyer). He informed me that his client had countered my offer with a number that sounded like their final offer and I asked to have it emailed to me because this guy was really shady and I wanted everything in writing. Two days later he informed me that the client's offer had been mailed via UPS (which I didn't receive because I was out of town). Then an hour later he sends me an email stating that the offer had been rescinded.

What I want to find out is whether or not he has to honor the original offer if paid before the deadline? Can a collector just keep making deals and back out at a moment's notice? It's not as though there was any new information about my financial situation he could have gleaned to believe I could pay more, he was just pissy because I asked for everything in writing.