On my credit card statement I have seen a transaction that has not been done through eBay or whatsoever? I can't solve the issue because since transaction does not appear on my PayPal activity I have no means to open dispute.
Check your subscriptions. (Discord nitro, Instagram, premium, amazon, netflix) etc and see if you've recently needed to update those via your card.
If none, check with your bank for this statement to see where it's headed. If it does not appear on your paypal history, it may mean that paypal has nothing to do with it. So a your issuing bank is more reliable here.
If you bought something online with a debit or credit card and did NOT log into your Paypal account then of course it won't show on that Paypal account because you bought as a 'guest buyer'. However your seller may have processed that payment using their Paypal 'card reader' and so Paypal would show on your bank or card statement.
If that is not the case then contact customer services AND your card issuer to query the transactions.
If you need to open a dispute for a 'guest buyer' transaction then you can.......
1. Phone Paypal customer services and see if they will open one for you (difficult at the moment due to covid) OR 2. Contact your card issuer for a chargeback.
Advice is voluntary. Kudos / Solution appreciated.
