Unilateral charging order

It has come to light that we have a Unilateral charging order on our property.  We are in the process of re-mortgaging our house and this was pointed out in the last stages of conveyancing for the new mortgage. This charge dates back to May 2012 and was made by Chichester County Court.  We have had no communication about this at all and were taken by surprise when this was pointed out.  My husband said that he had an incident at that time, whereby he had an accident in his car and damage ocurred to the named persons car.  He has a very unusual name, so after thinking back to what it could possibly be, he remembered the incident and that he had paid for all the damage and thought this was the end of it.  How can a charging order be placed on our property and we have no idea it is there ? 
I have all the details/reference numbers of the notice and we have been told to contact Chichester County Court to arrange for this to be cancelled.  But it is impossible to talk to anyone and get any advice on how to go about it.  Is it a case of paying expensive Solicitors fees, or is this something we can do ourselves ?  I have printed off a UN4 form, but don't know where to send it to and if this is actually the correct procedure. 
Any advice would be gratefully received.

Hi Denise - Are you able to give me the title number of the property so that I can look at the entry and how it was made?