If the company has threatened you with arrest/prison in writing, you should contact the Financial Ombudsman and make a formal complaint. Then you should contact the company to make a complaint and ask for compensation for distress due to their lies and threats. The UK is a signatory to the ECHR and: Protocol 4 ARTICLE 1 Prohibition of imprisonment for debt: No one shall be deprived of his liberty merely on the ground of inability to fulfill a contractual obligation.