Online license disk renewal debacle

Recently I processed a license disk renewal via payCity, I didn't finalise the transaction on the first time. But after completing the transaction with payment in full the service has not been rendered. After numerous emails the Senior Helpdesk Administrator recommended that I complete the first transaction which should not have been processed with payment and only then would they courier the disk for the second transaction which has been paid and then refund the full amount. Also they seem to be incapable of reconciling the number plate and a reference number, linked to the same vehicle. Instead claiming I requested two disks when the details for both transactions are clearly for the same vehicle. If I wanted the first transaction processed I would have completed the payment. Currently they are deliberately stalling and withholding the license disk and refusing to issue a refund. Also when I called the contact centre they requested my email address then pulled up information on two vehicles which I don't own so clearly whatever method they use to uniquely identify a drivers profile/record doesn't work. I would like to see the process finalised and then have no further dealings with them but they seem intent on dragging out the process, with slow correspondence and the Senior Helpdesk Administrator seems content to shift responsibility to nameless admins above her that provide no feedback. Any assistance would be appreciated as this company will not admit any error on their part instead and instead seem intent on getting their way through ************ like tactics.