Sheer disappointment

I was sent an email saying I owe money on my account and should use their link to pay the money which will reflect immediately on their side, which I did. A few days later, same amount was debited from my bank. Making it a double payment. They gave options if I want the amount credited or a full refund, I opted for the full refund. I have been calling and sending emails since June to get my full refund, only to be taken from pillar to post every time.