Coolant in Transmission

I have a 2004 Mercury Sable with 75,000 miles and a 3L engine. I took it to Domestic Auto Experts for regular maintainence. They did an oil change, replaced air, cabin air and fuel filters, and flushed the power steering and did a transmission flush and service. When I picked up the car I noticed a coolant smell after a few miles, an the transmission was not operating smoothly. the next day when I arrived at work, transmission fluid began pouring on the ground, and coolant was spewing from the resevoir hose. The mechanic says this is from a hole in the radiator and is not in any way

caused or connected to the service they performed. Can they have possibly done somthing to cause water to enter into the transmission?