If you feel that you are being persistently and aggressively harassed by creditors or their agents it could be found a criminal offence under the Consumer Protection from Unfair Trading Regulations 2008.
The regulations prohibit aggressive commercial practices, including aggressive practices used by creditors to pressurise debtors into paying their debts.
Some practices you may experience which may constitute harassment are:

• receiving alarming, distressful or humiliating demands for payment from your creditors by you, your family or anyone in your household
• being contacted too frequently or late at night
• being pressurised to sell property or to take out more credit
• being contacted and pursued by more than one collection company at the same time or not being told when the debt has been passed to another company
• receiving documentation which appears to have some official character when it does not, or receiving false claims that a document has some official character when it does not
• being pressurised to pay in full or in large instalments which you cannot afford
• receiving threatening gestures or statements
• having your claim of the disputed debt ignored
• experiencing public embarrassment by your creditor or having a third party informed about your financial situation, such as a neighbour or family members
• being given false information such as that action can be taken that is not legally possible, such as your property can be taken without a court order
• receiving correspondence including a business name or logo that implies the debt collector is a government body, for example, the court
• receiving implication that court action has been taken against you when it has not
• receiving implication that not paying the debt is a criminal offence.
  

The Office of Fair Trading has previously ruled that it is not acceptable for your creditors or debt collectors to try to obtain your whereabouts or contact details using neighbours or friends etc to pass on messages as this could lead to the disclosure of private financial affairs and to cause distress and embarrassment.
Any creditor following this practice should be reported to the Office of Fair Trading.
Your creditors or mortgage lenders are allowed to take reasonable steps to recover money owed including:

• sending you reminder letters and demands for payment
• telephone you
• calling at your home
• taking court action against you

If your creditors actions are causing distress or are of an unreasonable nature, for example persistent telephone calls or calls at work/at unsocial hours, you may want to consider taking further action.
What to do about harassment? You will need the name and contact details of the debt collection agency.
A debt may be collected by:-

• the original creditor
• a debt collection agency acting as agent for the creditor
• a solicitor on behalf of the creditor
• a third party who has bought the debt from the creditor
• bailiffs or sheriff officers in Scotland.
  

You could:

• collect evidence of the harassment
• contact the person who is causing the harassment and complain
• make a formal complaint, to a trade association, trading standards, the Office of Fair Trading, a professional body about a solicitor or the Financial Ombudsman Service.