So from my understanding, you shouted last call, as B bet 310k. Concluding your bidding time, than 2 players continued to bid after you called last call. Being fair you gave it to the true last bidder, which was a very nice thing. I believe you've done nothing wrong. Hope this helps a bit, if I got anything wrong please correct me! Last call should conclude the bids after you say it, like you did you gave it to B. So, Last call means you're taking your last bid.