Plett and Associates Extortion, harassment, illegal threats, for just double the going rate , Internet

I hired Plett and Associates in 2008 for calculating and filing my tax reports. They never asked me a specific professional question that would define accounting formulas, which resulted in me overpaying thousands of dollars in taxes.

When this incidentally came to the surface, the error was quickly corrected and lost income was restored (minus the new taxes + interest I had to pay for my now increased back income).

Through these years, I have been paying about twice the normal rate for the accounting service. Every income was paid in full and on time - including invoices for the years when my taxes were miscalculated. That is, I paid in full and on time for the years when I not only did not receive the service I was paying for, but did, in fact, receive the opposite - extra loss of income.

Now this accountant extorts an extra payment for the correction of her own error. She and her minions harass me and my children daily. She threatens legal action. Her argument is that it is MY fault that I am not accountant and don't know what information she needs to work properly.

If I were as well-versed in her sphere of expertise, why would I need to hire her in the first place?