I would just try to keep the line of communication open for sure. Let him know that you are worried that it is becoming a trend with him being late and insufficient. If he gets an attitude or refuses to stay in touch with you, too bad for him. Do you have the arrangements in writing? If so, does it say anything about what you will do if he doesn't hold up his end? I have held a vehicle for someone before from here and it worked out for me. Everything was discussed up front. There were delays, but I knew that may be a possibility up front. I would not do that for just anyone though, he had a flawless and extensive itrader rating.
"It's all good. We've caught a lot nicer shit than this on fire"