Excerpt from conditions of carriage
Article 12.2.
In the event of flight cancellation, diversion, or delays that will cause a passenger to miss connections, THE CARRIER will (at passenger’s request) cancel the remaining ticket and refund the unused portion of the ticket and unused ancillary fees in the original form of payment in accordance with this Contract of Carriage.
If the passenger does not request a refund and cancellation of the ticket, THE CARRIER will transport the passenger to the destination on THE CARRIER’S next flight on which seats are available in the class of service originally purchased. At THE CARRIER’S sole discretion and if acceptable to the passenger, THE CARRIER may arrange for the passenger to travel on another carrier or via ground transportation. If acceptable to the passenger, THE CARRIER will provide transportation in a lower class of service, in which case the passenger may be entitled to a partial refund. If space on the next available flight is available only in a higher class of service than purchased, THE CARRIER will transport the passenger on the flight, although THE CARRIER reserves the right to upgrade other passengers on the flight according to its upgrade priority policy to make space in the class of service originally purchased.
Source: Avianca.com / December 2016