Incorrect simple assessment

HMRC have incorrect employment records for tax year 2017-2018 and issued a simple assessment letter adding I owed tax. Under duress this was paid but on requesting employment records for 2017-2018 I found a company listed that I have never worked for. I called HMRC several time and eventually they agreed to raise an investigation and advised it would take approx 3 months to complete. I called HMRC several times for an update but was told conflicting information every time, but not once have HMRC contacted me to provide an update……..I have now received another simple assessment letter for tax year 2017-2018 advising I still owe money. Any advise or help will be greatly appreciated

Hi,
Unfortunately, it is not possible to check individual tax records through this forum, if you have a question which relates to your personal tax situation or tax code please contact our helpline:  
Income Tax: general enquiries
On this page you will also see a link to Personal tax account: sign in or set up which may be the quickest way to review information relating to pay and tax history, tax codes and how to change them. 
Thank you