to keep it short, but not sweet

accountant has claimed entrepreneur relief for me, but I only traded 7 months but company was kept open by him for just over a year.

HMRC rightly (apparently) saying I did not trade for over a year - just had company open for that long, therefore I will owe an extra 30% tax as relief not applicable.. as I paid only 10% on cash left in company.

looks like accountant entirely responsible for not knowing the law around this and I have had bad advice.

need some thoughts on legal action / routes of approaching / resolving the problem - with the accountant in the main, as well as payment schedules for HMRC