Correct me if I am wrong, but it seems you had a property which you subsequently left, and after an interval, you obtained a mortgage on a second property which has the usual mortgage charge over it. The first lot then caught up with you for the shortfall, sued you, won, and now want paying.(posted 8135 days ago)If they want a Charging Order over the property, with or without you paying a monthly sum - do accept this. A Charging order will claw any money off the sale to the limit of the debt if there is any excess after release of the original mortgage.
A Charging order is however a prelude in most cases to obtaining an order for sale and consequent dispossession - a lot depends on the amount of equity in the property and its worth as to whether a court will grant a sale order.
Your best hope is that they simply want to use the Charging Order as a means of hanging a sword over your head to ensure monthly payments, in default of which they would seek possession and sale in the same way as your current mortgagees would if you did not pay your monthly instalment. It might be a good idea to approach your former lender's solicitors with a view to a payment arrangement or, if you can do it, a lump sum settlement, before it gets to them proceeding with the CO which will add greatly to the costs which you will ultimately have to pay.