Sandra Munday

Good Morning, Looking for some advice please. I have requested a copy of the form I completed from HMRC to stop paying the married womans reduced rate NI I have asked for this by letter, in a telephone call, online and a further letter. I have just received a reply to my last letter that says my records show that I commenced the married womans reduced rate on 6th April 1977 and ceased paying at this rate on 5th April 1983. I thought the reduced rate ended on the 5th April 1977 and could not be claimed after this date? If they have this on my record why are they unable to provide me with a copy of the form they sent me that I completed and returned to them to stop paying this stamp. I am certain this was before 1977.