Accountant made a mistake and filed a wrong year of tax return before my LLC Co. even existed. PLS HELP!?

I formed my LLC in April 2004, never operated and we didn't even open a bank account. Within half year later, I filed dissolution of the LLC. My accountant took over a year mailing back and forth with the IRS and finally submit the right form. Since it's already almost 2 years, we required to file a tax return on 2004 and paid $800 corporate tax. But my accountant made a mistake and he also filed a tax return on 2003 which my company didn't even exist. Now IRS asking me to pay over $1400 for year of 2003. Now I hired a new accountant and trying to solve the problem, my accountant told me IRS not picking up her calls and now my accountant asking me to pay. I would like to know what is my option? Why IRS refuse to accept the fact that my accountant made a mistake? All they said is "I am sorry for what happened" and now they don't pick up their call. Please help !!!!