FedEx are trying to SCAM me over the purchase of a Gold Coin - Fed up with FedEx, please HELP!

I 100% agree with you , having problems the same as you with FedEx for 6 months now and still waiting for my refund.

I used them to claim back my duty I had to pay to receive the coins back into the UK, I paid the £53 and won my case 1 month on and still no refund of over £500.

they now hold your coins until you pay the fees, this loophole they use must be closed. 

In cases like this.  I only send one email asking the customer services team to provide the postal address of their legal department.  and then email the ceo directly.

https://www.ceoemail.com/s.php?id=ceo-9534

Fedex UK CEO is Mr Colin Groves, usually CEO's will not reply directly but they put their 2ic on it and a phone call from someone who can actually sort it usually follows.  Be respectful these are very busy people but I have never failed to get a satisfactory resolution when emailing the ceo of a company directly.