Incorrect national insurance number

I received a cheque for a tax refund, which was a nice surprise, because when I checked my personal tax account, I didn't think I had a refund due. Then checking HMRC letter carefully, I note that the national insurance number is completely different from mine, although all other details e.g. address, are correct. I tried calling HMRC but after 15 mins gave up. Should I bank this cheque or send it back??

Hi,

We would advise you to contact us before cashing the cheque. If you can call before 10am our helpline is quieter.

Income Tax: general enquiries

Thank you.