I was trying to keep this simple and give a general, wide advice of but, if we must get more technical LOL:: Trouble here is that we are in the realms of both mistake and passing of title.Imagine the dopey assistant in my jewellery example of a �100,000 ring being labelled �100 had gone on to take a �100 from the customer Having taken the �100 and then realising the mistake either then or later the assistant could refuse to hand over the ring. In neither case does the customer have a remedy..
In this case, notwithstanding that the money was 'handed over', received by the vendor, you have no remedy. The vendor could plead that there was a fundamental mistake which would vitiate any contract and, in any case, title has not passed in the goods ,there being no delivery.You are not to get an order for specific performance for delivery of the goods