My buyer fails to comply with the Agreement of Sale and fails to complete contracts on the completion date. This is due to a change in their own circumstances and through no fault of my own?

The purpose of ClozeSure is to protect you against your buyer failing to complete the property purchase, through no fault of yours.   ClozeSure will acquire your property and pay you the 90% balance (that is, the sale price less the 10% deposit paid by your buyer).  ClozeSure will do everything it can to complete its purchase immediately after your buyer has finally defaulted (usually 10 working days after the failed completion date).  This is not a guaranteed performance target, but ClozeSure will work hard to try and achieve it.