How do I cover my taxe audit losses when the taxes were prepared by a local business?

My taxes, since 2003 have been prepared by a local mom and pop business. I was recently audited for my 2007 federal taxes due to an unusual business deduction. I am a single person household with no kids and very few deductions. I give them a 1 sheet list of items that I think could be deducted with receipt, they do the rest. When I received the notice, I looked at what the IRS noted as an unusual deduction and they listed amounts and items I did not give them. Last night I looked at my 2008 return and it was the same. Now I owe around $7500 and more if they look at 2008. Which type of lawyer?