Friend audited by IRS and needs help?

A friend of mine was audited by the IRS for her 2004 tax return. In the initial communication, the IRS requested certain proof and doents which she promptly sent. Now she received a new letter stating that her return was adjusted and she owes $2,600 and must pay in ten days. She doesn't really understand why because she had her taxes done at a professional place located in NJ. It is called "Malqui Tax" which caters to the spanish population. She has done her taxes there for the past 3 years. They supposedly have audit protection. I advised her to contact "Malqui Tax" and have them provide audit defense but she can not get in touch with them. We googled the place and they have several locations in NJ and none of the phone numbers work. They are all disconnected. What can she do at this point? Thanks.