Bailiff chasing debt

[Miner745]

Where do we start defending my property against CDER who turned up at 06:25 and demanded payment of a speeding fine as apparently car registered from my property by my wife's son, when he stayed at our house in 2019, he was here for 3 months, never owned anything or possessions as just left the Army, we are now estranged have no contact with him what so ever, he has a property & lives in another part of the country, Bailiff said that he would get the police and a locksmith to gain entry (not true), ( I would not allow him on my property) and it got heated although he was respectful and retreated straight away, but how do I get the company to desist as stressful for wife and I will not leave house until threat of entry rescinded, we have sent proof of ownership & occupancy to the company and have spoken to CDER to tell them they have not completed due diligence to find his whereabouts but no answer as yet, any advice welcome thankyou is this a common mistake and how do I complain, the company seems not to care