SBC Yellow Pages & Re-aging of SOL

[foolsmission]

What is the name of your state? CA
I contracted in 1999 for 2000 book (my sixth year). Bought way too much add size and got behind. Sales rep comes to me with "new program":
1) Pay money order/casher's check and you can pay up front for an ad regardless of your current account being in collections with outside CA.
2) Four page contract makes no mention of old account # and says paid in full via money order.

Now Four years latter, when the former account (then and now in collections) WOULD have been SOL-barred they wrongly applied that segregated payment to the old account not the new "Cash and Carry". The new one was sent to collections as a separate never paid upon account to yet another CA who eventually resold it to first CA who now wants payment on both. When I contacted SBC and collections agency to offer proof of payment, and copies of contract terms, the CA said "we don't have to talk about anything but when you are going to make a payment". After a month, I got them to take a fax attesting to the above, they refused to even discuss the the failure to credit the payment to the correct place; per my instructions and contract's intent.
Clearly a violation of the Multiple Debts section of the FDCPA 810[15USC 1692h].
I plan to send validation and Cease and Desist about the phone calls seeing how they are incapable of listening.
Any advise or have others been the victim of this bait and switch re-aging scam?
They are of course threatening legal action (in days) as they've done constantly in writing since 2001.