Still waiting for my money to be refunded from Fedex

Fedex has given me the worse service you can expect from any service provider. Giving them one star is over rating this ridiculous Company. More than a month ago Fedex proceeded to deduct a large sum of money of my account by mistake. I then received a mail from them to acknowledge that they have incorrectly debited my bank account, with a message to say i must contact them to initiate a refund. The mail that was sent has no return address, and there was also no name or reference number to refer to. After approximately 20 emails sent to almost everyone in Fedex to date i have not received one response. The mail address i was given to address my request, keeps being returned as well so that does not work. I have tried for days to work with a chat bot and out of 20 attempts i managed to get to speak to someone who gave me more email addresses to send my request to. On my first attempt about 4 weeks back i received a reference number and a mail once again without any contact details, that my query will be attended to within 4 working days, needles to say i never heard from them again My general experience with the chatbot is that i get to number 1 in the queue and then suddenly it just says chat terminated and then it asks me to rate my experience. The numbers given to call does not exist or do not get answered. The email on the website does not work. I have once again sent mails, but i still do not know what to do, and my money is still not refunded. No correspondence from Fedex comes with any contact numbers, as they prefer not to talk to their customers. I have never experienced anything as bad as this, typical example of Zero Customer care. Other than venting my frustrations on this platform i do not know what to do any longer to get my money back. I receive monthly statements showing my credit, but it also does not get deducted from any new expenses, so they continue deducting from my bank account even although i am sitting with credit on my account with them.