I have been recieving emails from Pay pal and Ebay that seem to be changed by someone at yahoo.I wish to have?

I sold an item on ebay and it was paid for via paypal.l recieved emails from these companys notifying me of the sale and payment. Both emails showed an incorrect address for the buyer. The next day, this address was changed on those emails. Paypal says that this is not possiable with their computer. I believe that the yahoo computer is involved ,and that these changes are not coming from ebay or paypal.I think that they were changed by , after being recieved at yahoo,but before they reach me. I have photocopys of each address change. I wish for this to be investigated by yahoo. Roger Sisler