What do I do if not all of the discs are with the box set I purchased?

[lmcl3322]

I just received a DVD box set in the mail today. When I got home and opened the package I discovered that disc 4of4 is missing. This isn't the first time I've had a problem with missing discs in a box set but this is my first purchase from ebay and it's a bit more complicated to fix the problem I have. i can't exactly go back to the store and order a new one. If anyone has had this problem before please advise. 

[heidilynn0_3]

Hi imcl ..Have you informed the seller?

Yes , can be a pain. Here is your Buyer Protection..

http://pages.ebay.ca/help/buy/paypal-buyer-protection.html

If can't be worked out with seller and protection is the option , be aware that PP requires return at your expense with online delivery confirmation. Signature if over $250. US.

[heidilynn0_3]

PS.. Have 60 days to leave appropriate feedback and DSRs.