I really wish that riot would not disable items mid game

I was playing thresh support, and was trying to get a Zz'rot portal, not to abuse it, which i didn't know about at the time, but to just use it to push lanes. I had both of the items that build into it, i was just 400 gold short of the combine.

So, 1300 gold later when I finally backed, it was much to my dismay that I could no longer buy the item. And with the way the game was going, there was 0 reason to pick up a ohmwrecker, as we were starting to lose, or to get an abyssal for my all AD team.

Riot, i understand when you see a problem and want to fix it, but for those of us playing the game, the 0 heads up makes it really hard for us to adjust our builds when we are already 75% done with the item and now can do nothing with the parts.