Dependance on non-punctual people can actually ruin your reputation in a big way. Many times, either in social or in professional circumstances, we are depending on people who is arranging some programme or meetings for us. And if that person is not prompt and quick in communication, the final blow of bad prestige comes to you. Imagine you are going to have a meeting with a senior person, which is arranged by a person who turns up late and has remained non-communicative either with you or with the senior person, or with both. Resultantly, you happen to be late in the first meeting itself, without any of your faults. In such condition, the first impression of yours in the mind of that senior person will certainly not be positive. And it is purely because of the middle man who is not respectful of time. S/he has not much to lose but for you to undo this damage might take ages.
It's difficult to change the circumstance when you have no other course but to rely on the middle man. It happens that such people are also not very genuine in sharing information. They might belong to the class of people who say 'reaching in five minutes' but turns up after half an hour. And especially in the time when you have no communication with the other party and also no means to reach out directly to the meeting, you are only at the mercy of the person.
It is not easy to comprehend how to deal with such phase because the problem lies in habit and attitude. If the individual does not realise that what s/he is doing can damage your respectability, how would s/he improve? It is very normal for them to turn up late, and not feel bad about it. They also consider giving misinformation about timing is a favour to you, lest you might get blood pressure! So in their mind, they are doing right thing. They also consider a few minutes here and there very much acceptable. Not giving a call when required is not a big deal for them. So no problem exists in their mind at all, it is unilateral issue that belongs to you, and you have to resolve it yourself.
Well, everyone have their own ways to deal with such an incident, but perhaps one solution might be to ask the person to come early, in the pretext of some other work. Thus combining two works where the first one is a shield to bring her/him on time is a good way of getting hold of that person. Another option is that you can reach earlier to her/his place, before time and take the person in your car before time and engage her/him to ensure that you reach to desired place puctually.