I sent in my dispute, and I got a letter back asking to please fill out my license number, full name, social security, and address so that they could complete the investigation. Is this mandatory to fill out before they'll look into it any further?

did you send that info when you requested your dispute? if so...dont fill out the form. its a stall tactic which will give them another 15days. if they dont respond in 30 to your request, send another letter stating time is up..delete...

I sent them most of the info already. I'm just worried they can just send me back what I sent them and tell me it was verified. But maybe that's not how it works.