Oh dear.  The real problem is that eBay's time limits are strict.  If you miss this you are simply too late. 

All you should have done is opened a "not as described case" with eBay through their "money back guarantee".  You do not contact the seller to discuss/argue; opening the case does that.  It also notifies eBay.

Another problem is that you should not have tried to improve things by long words with Microsoft and [presumably] adding or modifying the software.  

All you can do now I'm afraid is to contact your credit card or payment provider to see if they will help

@suedonym2