I live in NSW / Australia. I have been dealing with my accountant for the last 15 years . I used to pay him between 300 to 500 Dollars per year for my tax return as a sole trader . For personal reasons, I did not lodge my tax return for several years then when I lodged them, he sent me a tax invoice where he inflated his fee 10 folds then he is suing me to pay it . What should I do ?