Sued for Fraud

I've been reading the forums extensively and understand that I should send a certified letter for debt validation to the collection agency that's hounding me (Collect Corp for AmEx). The problem(s) I'm having are as follows:

CA called on August 2 requesting that I pay the credit card debt in full via direct deposit (ACH) within 48 hours. I gave them my checking information and said that the funds would be available on August 4. In reality, I didn't have the funds available, but I was going to find someone from which I could borrow the money (i.e. family). CA called on August 3 to confirm that the funds would be in the account and I said yes even though I still didn't have the funds in the account (I was running around like a headless chicken trying to move my family into a new home, wasn't thinking clearly, and was rushed to get off the phone--my mistake). Later that evening, at 11:50PM, I called and left a message to the CA that I did not have the funds available and to stop the withdrawl from the account on August 4. Apparently they did not get this message and went on to withdraw the funds. My mistake, but I was scared as heck due to the threat of litigation.

It is now August 11 and the CA calls everyday to ask if/when the funds will be available (being very rude, I might add). Then the representative tells me that I can not only be sued for the funds, but also for fraud in my saying that the funds will be available when they actually weren't, despite my message saying to stop the ACH withdrawl. Yes, I did initially authorize withdrawl, but I then retracted authorization afterward. The rep. said that she did not get the message to cease on the withdrawl and I don't have my own proof that I left the message--only proof that I made a phone call to the CA at the specified time above on my cell phone.

The CA rep. said that she will give me until August 12 to come up with the funds or she will advise AmEx/CollectCorp to proceed with litigation charges for both debt collection and fraud.

What I am wondering is:

- Is it too late to request validation given the CA rep.'s ultimatum?
- Despite my phone message (did not speak to the CA personally, nor did I put it in writing), do they have real grounds to sue for fraud? I would imagine that they keep records/recordings of all phone conversations, so the proof lies within the CA.

There's no doubt that family will help me, but they can't help as immediately as the CA would like.

Any advice would be greatly appreciated.