Alliance Asset Management

So I had this 300 dollar loan with Check into Cash. They apparently sent the debt to Alliance. I have since changed cell phones and they have been calling my job. They have threatend legal action against me over and over. I have only dealt with them on the phone 3 times, but they are so rude! So today I get this call from them, that I had promised to pay and I didnt. I told her something came up and that I wasnt able to. She said I had until the end of the day to call her if i got the money... anywho, I decide to send a DV letter, I have one all done, and I realize they have never given me an account number, so I call and the lady that answers the phone, just says, what do you want? I said very nicely, can i please have your fax number? so she gives it to me. Then I say, you know, i have recieved some calls that i have a debt with you, and I would like to get an account number. No one has ever given it to me. So with my social she quickly finds it. She suddenly starts yelling, You just got off the phone with Marie and you told her you weren't paying! why do you want the account number?! the debt is already going to an attorney in your area! So i interrupt her. I told her, I just got off the phone with Marie 2 minutes ago! she said if i had the money by the end of the day to call her back, obviosly my account is still somewhere in your building, can you please transfer me back to her... she says no, you had your chance... and hangs up on me! My questions are: 1. can they sue me for 300 dollars? and 2. can i still send the DV letter without an account number? BTw... i live in California and also, I have never recieved any correspondence from this company.