Simple Assessment calculation - paid but total may be wrong

Hello. I received a simple assessment calculation for the first time in October, and have paid the additional tax which was calculated, but having checked at work, I now believe that the calculation may be wrong. The message with the calculation is dated 09 October with a 60 day window for changes, which has passed. Is there a way to amend this beyond the 60 day window? Thanks.

Hi

All queries need to be made within 60 days of the issue date of your PA302. As your Query is now late, we cannot deal with this over the phone.
You will need to put your query in writing to HMRC providing your reasons why your Query is late, and also the reasons you disagree with the calculation.
We will consider your claim and let you know in writing if your query has been accepted or not and any next steps to follow.
Please include your National Insurance number on the first page of your letter and send it to

Pay As You Earn and Self Assessment,
HM Revenue and Customs,
BX9 1AS,
United Kingdom.

Thank you