Now, the seller does not have record of this second chance offer being agreed to and, as a result, this offer is not passed onto me.  I am most dissatisfied with eBay for not fulfilling this side of the bargain.

What has ebay got to do with it?   SCOs come from the seller, not ebay.

The seller can send out multiple SCOs and if you left it till the last minute to accept it the seller could have already sold all the items that were available.

I really wish you wouldn't give advice on things you know nothing about.

Sellers can only send out second/third/fourth chance offers if they have enough items to cover every offer they send.  If they don't have them available they risk a defect for items not being in stock.  If a seller sends out a second and third chance offer it's not a case of first in best dressed.  Every person who gets an offer is able to buy the item offered to them.