Amended taxes

Hi all,

This might be a lengthy post, but I received a bill from the IRS back in January saying I owed $4,101 for an increase in tax.  My account (whom I no longer use) forgot to include a W-2 form for my job resulting in $82k in unreported income.   When I brought this to her attention, she said she would Amend my taxes for 2017 and correct the mistake, she then followed up with me two days later (again back in January) saying I'll be receiving close to $3k in additional refund.  Here's where it gets super annoying, I received a letter from the IRS saying I owed $4,779.28 that includes interest and penalties.  My current accountant is going to handle for me and I already called the IRS to get an extension for 120 days but I don't understand how she claims I would have gotten an additional refund.  Aside from reporting my previous accountant to the IRS, is there anything that can be done to hold her accountable?  I'm freaking out about having to pay close to $5k for this error when had she just done my tax return correctly, I probably would have gotten more money back.  If anyone has insight here, it would be greatly appreciated.  Thanks!