It has been spelt out to you numerous times though. Of course it's not going to be the easiest thing to do, but you've been bleating on for 5 pages, could have done it in that time.
Go to get the refund, or tell them in a letter and verbally as you give them said letter, that if you don't get it, then you will that afternoon put a claim into the courts, using Ekona's link
Then you either get the refund (including part ex-value, as that was part of the consideration for the 350z), or you start the court business.