Fasttrack Reclaim HMRC scam

Murf65

I received a P800 letter from HMRC early July 2023. They said I had paid to much tax and was owed a refund which I could claim by signing up to their official Gov website, this I did and made and received my refund about 5 days later. Move forward to last week (mid Sept) I received a letter from Fasttrack Reclaim saying "congratulations on your rebate from HMRC" and quoted the exact amount of money I had received, but now, it was time for me to pay them a percentage which I owed them as I used their company to make the claim, I did not use this company, as I have already said, I made the claim myself. I have had no contact with this company regarding my tax refund. This morning they called me, I told them this was a hoax call and put the phone down. I have now received an email saying "we tried to contact you today", gave me a reference number and told me to contact them. The email was in my junk if that's any help.