I booked a room from booking.com just for the visa. The room that I booked didn't require a credit card information and I did the booking without reading the conditions.
Now I noticed that 320 CAD is required for cancellations. I sent several emails to booking.com but no one replied so far.
Did anyone face such a situation before? How could they take the money without credit card info?
What you probably should do right away is to contact the property (not booking.com), notify them about your cancellation and wait for their response.
Properties accepting this kind of reservation know the risk, and gamble on it. A part of the gamble may be that the property is popular, or located in popular place, so they might have no problem rerenting your room given enough advance notice. Even if they don't, the question about cancellation fee might not pop up. And if it pops up, you'll have an idea how the hotel would expect you to pay that fee, and how would they plan to enforce it.
Now, there is no guaranteed way for the hotel to get this fee. But there are several ways the hotel can try it:
They can send you a bill to your billing address (it is up to you to pay it);
They might be able to sell this debt to a collection agency (this is questionable);
They may sue you (in Canada - I assume it is Canadian hotel since your booking is in CAD), and get a judgment against you. Then they would collect as any other judgment. They might also be able to sue you in another country - like in US - if the conditions (those you didn't read) force you to agree to a specific jurisdiction. If you visit the city but just intend to stay in a different hotel, this is not even difficult.
The amount in question makes the court action unlikely, though, as suing someone is expensive, and one still might not get any money back even by winning the case.
However even if they do not get their money back, there still might be consequences. For example, the hotel may refuse any further reservations from you in future. If they exchange information about non-payers - this is typical, for example, with HK "hotels" operating under the same terms - none of them would make a booking for you. Or they might accept a reservation, and try to charge you this fee upon arrival. So it is still better to resolve it.
There are a few locations where Booking.com handles payment for some hotels/guests, but I don't think Canada is one of them. In the overwhelming majority of the cases, customers don't hand over any money to Booking.com, nor will Booking.com collect any fees from customers. It's up to the hotel to collect the money. Having a cancellation fee, but not requiring credit card info is a bit unusual, but it may happen. Now, it may happen that the hotel contacts you, asking for money as a deposit (check your reservation confirmation, if the hotel has a deposit policy, it will be mentioned there). The hotel may cancel your booking if you don't deposit, but that was your intention anyway.
I don't think anything bad to you will happen. Without credit card information, there's no worthwhile recourse for the hotel to take.
Now, Booking.com customer care not quickly responding to email is unusual. Feel free to call them -- customer care is reachable 24/7, having agents speaking over 40 different languages, and from most countries, the call is either free, or will be charged as a local call.
I do frown upon your actions though. Your actions hurt the hotel, hurt Booking.com, and you're trying to get access to a country under false pretenses.
possibly, they just preauthorised the amount on your card. sometimes on booking.com, when there is an option that you do not have to pay immediately, a hotel does preauthorisation = freezing the amount, to make sure your data are true. in the credit card slip it looks like payment, but it is not, it is back few days after. but customer service should clarify that for sure. be persistent and good luck.
