Rivals charging me coins to win?

Good morning, 

I played a rivals game last night in div 4 if that’s of any relevance, I was 2-0 up by the 30th minute and my opponent quit the game at that point. Tell me why my coin balance was 4,821 lower before and after that particular game, and just to rule it out I had not bid on any item on the transfer market for those coins to disappear.  

I’d like an explanation as to why this happened from an EA employee if they are round this forum.