So frustrated with Fedex billing department

Customer service (account department) I have been trying to get a response from the FedEx billing department for a week now. They are not responding to my email and when I call their customer service, they cannot help because apparently, their billing department is in India. My account was revoked due to outstanding payments. I have paid what was required and sent proof of payments but no one is confirming if the payment was received or not. Moreover, there is an incorrect billing on my account that I have a query and no one is giving me answers. I send multiple emails to customer service and billing service, but still no response. I don't know who can assist anymore.