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Given all of the information you have provided, I feel completely accurate saying, you might want to read this.

Did you get an unopened box, or just an activation code? If the latter, than read the above link.

OP, don't make your judgment on that thread. The person who made that thread wasn't too smart. I'm not going to read that entire thread, but it seems like he doesn't know how eBay or PayPal work... to wait 52 days before trying to do something? If I didn't have a code within a few days, I'd file a dispute immediately.
 
I bought Applecare on eBay - so far, so good. Still listed as covered, etc. Just keep your receipts (both your original and your eBay AC purchase) and (hopefully) all will be OK.
 
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