Hi I am self-employed and have just began receiving letters from Fredrickson Internatinional re overdue NI contributions for £500. They have said their next point of action is for an HMRC officer to visit me or for court proceedings. Does anyone have experience of this? Should I make contact with this company or contact HMRC? I don't want to make contact with Fredrickson as I know they have a very dodgy reputation. Thanks