Bringing a recording device and using it in a courtroom without permission is a serious offense. I'm not sure about consumer tribunals, better find out and ask first before getting into big trouble.
Lawyer speak: contempt of court

This post has been edited by Catnip: Nov 24 2012, 05:46 PM

My simple advice.
The seller had his chance and he blew it.
There is no longer the need to communicate with him except at the tribunal.
You are within your right for a full refund + compensation. Do not ask for anything less.
If the president ask you why, just say you have lost all confidence and trust in the seller.
Bring your phone with you and print out screen shot copies of the conversation and submit it as supporting evidence during the tribunal and let the president of the tribunal make his judgement of the character of the seller.

Finally, use the money to buy a new one here.