Is the addressee a limited company, it would seem so?
If so, then you, as in 'I', have no legal standing, the owner and liable party is the company. You might own/manage/otherwise work for the company but liability rests with the company.
On which point, after the company had lost their appeal and they were served with an Order for Recovery(which you refer to as a 'letter from Northampton County Court') what does replied requesting additional time due to my mother...
..It was granted after that no correspondence.
mean?
An OfR gives the recipient 21 days in which to either pay or submit a witness statement or statutory declaration citing one of the specified grounds. Requesting additional time is not one of these.
So your account is not clear as regards formal legal procedure.
Also, within approx. 5 weeks after losing your appeal the council would have written to the owner with a Charge Certificate. What happened?
Time is not the owner's friend and you must act by tomorrow (27th) at the latest
IMO. But before suggesting how, you must answer the questions fully please.