Are you sure this is not a phishing email? Do not click on any links in it but go to the site in question. So check your Purchase History page, and your Paypal account. If the transactions are not there, you have received a phishing or scam email, just delete and ignore it, or forward to spoof@sbay.cim.
If the items are there, your account has been hacked. Change passwords on all accounts now. Inform eBay CS, Customer Support asap. Go to the Help & Contact tab above, and into the bar type in Someone Has Used My Account. Follow prompts to Call Us and inform them of your findings.
If Paypal has also been compromised, call them too, and probably need to inform your bank.
