National insurance contributions incorrectly applied

Dear HMRC, I have paid voluntary NI contributions, and despite making it clear which year to apply to, your agent has incorrectly applied them. Please help complaint number  Thank you

[Personal information removed - HMRC Admin]

Hi T K,
I am sorry to hear of voluntary National Insurance has been allocated to a tax year that you did not intend it to be applied to. You can call the National Insurance helpline so they can investigate the tax year you intended it to be applied to.
National Insurance helpline:
Number - 0300 200 3500
Overseas - 0044 191 203 7010
Open - Monday to Friday: 8am to 6pm Closed on Saturdays, Sundays and Bank Holidays
You can also write into HMRC including you National Insurance number, name address and the amount you paid to be applied to the tax year.
National Insurance Contributions & Employer Office
PT Operations North East England
HM Revenue and Customs
BX9 1AN
There is no complaint number to call but you can raise a complaint through the attached link or when you call the helpline -
Complain about HMRC - GOV.UK (www.gov.uk).
Thank you.