@14gs14
You are a buyer
You bought an item, paid for it?, and then asked the seller to cancel the order.
Your problem is that you have not been reimbursed your payment.
Right so far?
You should know that credit card payments are not as simple as they seem.
First you are not actually paying.
While the seller is getting money (fairly quickly) the card is actually making you a loan, and then sending the money to the seller.
In order to reimburse you, they have to first get their money (which they loaned you) back, again fairly quickly, but then adjust the balance on your credit card, so that the credit that was removed is put back.
Have you looked at your credit card balance for the reimbursement?
The second was a Best Offer for $15,000 which you withdrew?
If this was an Offer, you would not be charged by eBay unless the seller accepted the Offer yet you say he was not aware of it.
Was this a vehicle?
Did you find the vehicle on another site like FBMarketplace or AutoTrader?
EBay does not handle the finances for any other site.
This sounds like the scam named the Kubota Tractor Scam. The vehicle does not exist.