If you were able to cancel a payment it means the seller made a mistake with the email address on their auction and could not accept your payment.
When you pay a seller it is never instant > paypal credit the seller for you and then start the process of uploading your funds to paypal from your funding source.
This is done so you get your item more quickly.
So when you cancel that payment (as the seller can't accept it), those funds can't do a u-turn > they have to process through to paypal who will then either return them to your funding source (if you paid with a debit or credit card), or credit your paypal balance (if it was funded from your balance or instant bank transfer), but that takes a few days and sometimes up to a week.
Advice is voluntary.
Kudos / Solution appreciated.
