Incorrect Rebate

Hi I have received a cheque for repayment of overpaid income tax for 2020-21 It was a rebate from a pension i cashed in - HMRC already paid the rebate in April 2021 - after sending in a P45 and claim form. I haven't completed a self assessment since the year 2019-2020 so am unable to log on to the HMRC site using the Gov Gateway as i have no ID other than my driving licence! I have tried calling but after waiting an hour on the phone unable to speak to anyone...can you tell me where i should send the cheque back to.

Hi MGILDEC,

Please return it to our Income Tax department with a covering letter confirming your name, address and National Insurance number.
Income Tax: general enquiries

Thank you.