What do I do if an employer wont send me a 1099 for independent contract work I did for them last year? And how do I go about getting their EIN?

I did some independent contract work for someone last year, but thy refuse to send me my 1099 so I can file my taxes. I have kept record of all the money I made from them, so the only real piece of information I need from the 1099 is their Employee Identification Number. How do I go about getting this without the 1099?