Yes, the majority of hotel reservations are fully refundable as long as you cancel prior to the hotel's cancellation deadline, which in most cases is within 24 or 48 hours of your scheduled arrival. If you have a non-refundable reservation, it might still be possible to cancel it and get a refund within a 24-hour period of booking. Enter dates in and click on "Search", then you can filter by "fully refundable" to get the best deals available near Plaza General San Martin.