Given a travel related situation, and given a specific question about the situation, summarize the question into a title

[EX Q]: On November 28th, 2014, in Moscow, the airport Domodedovo, I had my valid ticket to the U.S. going through Moscow-Frankfurt => Frankfurt-Toronto => Toronto-Minneapolis, MN. I hold a F-1 U.S. visa, and am a citizen of Tajikistan. When I came to the check-in counter, handed my passport to the representatives to print me my boarding pass and check my luggage in, they told me I needed a transit visa transiting through Canada, not going through Germany, therefore they did not check me in nor gave me my boarding pass. I checked Canadian embassy whether I needed a transit visa it says YES. below is the snapshot:

Then I tried calling the Canadian consulate in Moscow but there wasn't anyone assisting visa questions. I tried calling the ticketing agency I purchased the ticket from but they weren't any helpful in rebooking different tickets using the same airline before my departure time. At the end I was forced to buy new tickets to fly to the U.S. My questions or was my ticketing agency supposed totl inform me via email to get a transit visa? Was it a legit reason for the representative at a check-in counter in Moscow not allowing me to use my ticket? Would I have a good reason to claim a report for some kind of refund saying the agency didn't inform me I needed a transit visa? Or is it always up to the travelers to know they need it?

Thanks! I'm just a full-time student and spending extra $650 is just too much for just not knowing about this Canadian transit visa.

[EX A]: I wasn't allowed to travel internationally because of Transit Visa. Is it a legit reason for not using my tickets?

[EX Q]: When I came to Chile, I originally thought I would only be here for 1 month, so that's what I put on my tourist card.

However, now there's a good chance I'm going to stay the full 90 days that my tourist visa allows, and I might even want to extend my visa after that.

Can I wait until the 2.5 month mark to extend my visa, or do I need to extend it 2 weeks before my "declared" trip ends (i.e., within the next 2 weeks)?

[EX A]: Extend my tourist visa toward the end of my "declared" trip or wait until closer to the visa expiration?

[EX Q]: I received my Iranian visa two days ago. My plan was to go there for a week, but unexpectedly I have an extra week available (due to an event in Turkey being cancelled just recently). Therefore I would like to extend my stay in Iran - to be precise enter the country before the date I put in my application. The itinerary would change a bit too.

Is this a problem? According to the date printed on it, my visa is valid for the entire period. Do I have to notify the embassy or the Police Department of Foreign Affairs or the party, I got my invitation from, about these changes?

What is the best way to handle the situation? I don't want to run into any problems, but I also don't want to miss the chance of spending some extra days there.

[EX A]:
Travel changes with an Iranian visa