I included in my 2020-21 return all income received a large part of which related to pension arrears dating back to 2008-09. I attached the letter from the pension scheme administrators but this was ignored when the tax calculation was made. I subsequently sent a letter in November which should originally have been dealt with by 21 December, and now should be dealt with by 4 February(!). I have paid the amount I believe is due but there is a large sum showing as overdue. Should I pay this to prevent the bailiffs turning up?