DENVER Frequent flyers at the Denver International Airport had a smooth ride when it came to the airports shuttle service on Thursday afternoon. But just a few days before, things got a little bumpy.Passengers were impacted by exceptionally long wait times for shuttle buses last weekend after unexpected sick callouts by drivers.On Sunday, we experienced a lot of callouts. We had over 26 drivers call in sick, said Mark Nagel, the senior vice president of parking and commercial transportation at DIA.Denver7 Investigates obtained videos and photos documenting the long lines of passengers waiting to board the buses. Watch our previous coverage below DIA scrambles to explain shuttle bus delays over weekendI felt sick to my stomach, said Nagel, reacting to the airports own cameras showing the crowd of customers. We let down our customers We deserve to give them better service. And we will.An open records request filed by Denver7 Investigates found at least a dozen complaints from passengers about the shuttle system last weekend.One read, My pregnant wife and I stood in line for an hour last night hoping to get back to our car in the Pikes Peak parking lot. I simply wanted to express that we perceived the quality and timeliness of shuttle transportation at DIA to be poor and unacceptable. Please re-evaluate your contract with the company responsible for this area of airport operations.Another read, "I've flown out of here hundreds of times in the last 5 years and I've never seen anything like this. You really need to get your s*** together. This is unacceptable.Nagel did not disagree.The wait times that we saw on Sunday evening were unacceptable and we are doing everything we can to fix that so it doesn't happen again," he said. The shuttle bus service is operated by LAZ Parking Midwest, LLC., a third-party company contracted with DIA. LAZ Parking is a new company that took over operations on Feb. 1.Denver7s open records request found other complaints about shuttles dating back to mid-February, with some specifically referring to employee parking lots. We receive a couple of complaints a week, said Nagel.When asked about the complaints submitted prior to last weekends debacle, Nagel said, The contractor allowed numerous drivers (to) go on break at the same time, which were on the same route. So, if we have eight buses operating on a particular route, and we give two or three drivers a break at the same time, well then that reduces our numbers of buses running that route.Laz Parking provided Denver7 with the following statement, "On Sunday, LAZ Parking Midwest, LLC encountered an unprecedented staffing shortage in our shuttle operations at Denver International Airport when an unexpected number of drivers called out sick. This led to extended wait times for both travelers and airport staff. We sincerely regret any inconvenience this may have caused, and we have since implemented contingency measures to ensure reliable service during future staffing challenges.According to Nagel, the contractor and airport are addressing the issues by implementing the following: Offering overtime Scheduling on-call drivers, who are available in the event others call out Staggering drivers shifts to ensure breaks are taken at separate timesFrom the airport standpoint and even the contractor standpoint, we should have been able to handle any amount of call-outs for whatever reason. Unfortunately, on Sunday, we just couldn't do that, said Nagel.According to Nagel, passengers who were impacted by the delays can request a refund by emailing park@flydenver.com. They must include their parking receipt. Several passengers told Denver7 Investigates they called ride-share services to transport them from the shuttle pick-up to their cars instead of waiting in line. DIA said it will not reimburse ride-share expenses. ...read more read less