This seems to be a new, but trending, scam. Revenue and Customs are aware and offer advice:
“Do not telephone the number provided, or provide anyone with your personal details, including your bank or credit card information.
“HMRC is aware of these automated phone call scams.
“To help their investigations you should report full details of the scam by email to: firstname.lastname@example.org, including the:
– date of the call
– phone number used
– content of the call.”