We missed a connecting flight out of Bogota, Colombia with Aeromexico, due to an airport closure in Cartagena, Colombia. Avianca airlines gave us an endorsed letter explaining the issue in Cartagena and explained that most airlines would honor it and not charge for ticketing changes as a result of the issue. We tried to call Aeromexico's customer service but we were outside of their hours of 7am to 6pm. We did email in the letters from Avianca and received an automated response and a claim number stating someone would be in contact shortly. Upon arriving in Bogota the following morning, we waited in line at the Aeromexico check in counter to speak with a representative. They told us they could not help us and that we need to speak with customer service first. We tried a few times, waiting on hold for an hour each time. When we finally got through and started to explain the situation, they disconnected the call each time. We did not care if we had to pay a change fee but we needed on a flight as our negative covid results were time sensitive. All representatives from Aeromexico refused to do anything for us until we spoke with their customer service call center. Due to time and Aeromexico's refusal to rebook us on one of their flights, we were forced to purchase tickets on another airline. Avianca even tried to speak with Aeromexico representatives at Bogota International Airport to help get us on a flight with no luck. Avianca tried to get Aeromexico to release/transfer our unused tickets over to Avianca so they could look after us and Aeromexico refused. Aermexico's customer service did not respond to our concerns until two weeks later, when all we wanted to do was use our exiting tickets to get home.