At the time that the vehicle was seized, a warrant would have already been issued against your ex partner. Most significantly, the warrant 'binds' the goods (in this case, the car). In simple terms, this means that the vehicle cannot be either sold or transferred. If it is, (which is what has happened), then the vehicle CAN be seized.
As your ex partner was the registered keeper at the time of the various contraventions, then sadly, he is the person responsible for paying the debts. As such, it would be for him...and not you....to submit Out of Time witness statements. He would be able to make such applications on the basis that he had not received any of the statutory notices. In doing so, he would need to outline the reason WHY he would not have received any notices.
As I understand it, there were five separate parking contraventions. Therefore, there would have been a total of 15 letters from the council (Notice to Owner (NtO), Charge Certificate and Order for Recovery). In his Out of Time application, your ex partner really should have elaborated on the reason WHY he had not received these notices. Instead, he has simply stated this:
'No Notice to Owner was ever received by myself, I WORK AWAY AND HAVE A 'COA' ONLY.
Your ex should have provided far more detail as to WHY he did not receive the notices. For example, was he working abroad? How long was he working away for? Did the person in charge of the 'care of' address notify him of correspondence? How often did he return to that address?
Taking the above into consideration, I would be surprised if his applications were to be accepted. It normally takes approx. 4-6 weeks to receive notification of the decision.
Did your ex provide the 'care of' address in his application? If so, has he taken steps to ensure that correspondence reaches him?