Wrong middle name

Hi, I have recently received letters from hmrc addressed to my correct forename and surname but with a totally different middle name. I have no idea where this middle name has come from. I have logged into my government gateway and all of my details are under my forename and surname only - nowhere to state or view records for my middle name. Can someone advise how I can get in touch to ask them to either remove or change the middle name? Thanks

Hi,
You can see our contact details here:
Contact HMRC
Thank you.