2003 Pontiac Grand Prix Fuel tank overflow when filling

None of the listed categories seem to fit my problem. I had my fuel pump replaced today and when I went to fill the gas tank I found it was taking an unusually high amount of fuel to fill. (I later checked the owners manual and GM states the capacity is 17.2 gallons) When it reached just over 19 gallons I stopped and then noticed there was a stream of fluid flowing from under the vehicle. Looking up from underneath the rear of vehicle I could see gas pouring down the sides of the tank. Could the repair shop have affected a float or gas level sensor when replacing the fuel pump thereby disabling the device or action that would help prevent this type of incident from happening? I am the original owner for 6 1/2 years and have never had this happen.

Thank you