Is an accountant liable for not incorporating my business?

Hi, I asked my previous accountant 3 times whether i should be a sole trader or a limited company. The first time when i set up my business in July (by this time my PAYE from my previous job for the tax year in question was already close to the 40% tax bracket). The 3rd/last time I asked (a few months later in the same tax year) was when my total earnings for the tax year had reached 6 figures. My business, costs and trading were fully known by my accountant and they had committed in writing to making my income tax as efficient as possible. I was finally incorporated in late January of the last tax year - 6 months after setting up my business and after generating a 6 figure total income for the tax year to that date.

This is not a 'kick the accountant' question. More a genuine desire to know whether the accountant (by not providing any information on the risks/benefits of sole trader versus limited company status when asked 3 times which was the most efficient status - and by stating in writing that they were on top of my accounts and would make my accounts tax-efficient) was potentially negligent in their advice and action? The accountant had committed in writing to taking care of all communication and interaction with HMRC and had stated in writing that they would minimise my income tax. I changed accountants last year as I felt I could not get proper answers.

My new accountant has just completed my sole trader accounts and self assessment and, as a consultant with relatively low costs, I now have notable excess profit liable to tax at 40%

My new accountant has stated that a limited company would have been far more beneficial to me tax-wise and that the decision not to incorporate will result in tens of thousands of pounds additional tax payment.

Am i being unreasonable in expecting to have a case to seek some form of financial redress? Or is it simply a case of you win some, you lose some when it comes to accounting advice? Note my accountant is ACCA accredited.