I recently had my account hijacked and I had problem with ebay in changing my password as the hacker kept listing and Live help was no help & Security Live Help was tempoarary offline. After my experience, I realized there was something I could have done first but I didn't know it at the time.  Here the step you should take

1.  If your password been changed, immediately get out of your ebay account and click forgot password.  Ebay will send you in email and a link to change your password.  They will asked you several questions that only you will know.

2. If you cannot find Security Live Help, go to Regular Live Help to get the link.  Normally, you are waiting for about 10 minutes so while waiting do the next step.

3. Post a blog and let the blog fellow know your account had been hijacked and they will help you by reporting to ebay that the auctions is not your.

4.  Wait for email from ebay that show that all the auction had been remove. Never remove the auction yourself. 

5.  There is still more step as you do not have full access to your account.  I found the step when I try to ask questions to other ebayer but I couldn't because ebay recognize that my account had been hijacked and needed more proof in who I am and there was a place where I click.  Ebay will call your phone number and give you the code and then you may enter the code and have full access to your ebay account.

Paypal and Ebay account should never be the same password.  If they are the same password, you will need to change paypal password also.

If possible, try not to include your phone number in payment & primary shipping but must include in registration. 

I hope this will help you get help fast and to stop the hacker fast.