User Activity

I have customers who make bank trasfers , but their payments do not show on my bank statements?
What do I do as a Seller when a customer receives an empty parcel ? 
Why Does Pay Pals Dollar Conversion Rate differ to Global Pricing when Buying an Item Out side of Australia. It is always 2-3 cents wrong
I am trying to find out 'what is the best END TIME to Auction a Car on EBay Australia . your help is Apreciated .:-)