Welcome to WAB, BF!
I would personally suggest
humane traps, then relocate
as best you can. If they're breeding, I wouldn't like the thought of the parents getting killed and the poor young waiting for the adults to return, then slowly starving to death. That said, I would also advise against blocking off the hole in your garden -
or they may just look for somewhere warm to reproduce... 
Try ultrasonic units, or leave food out away from your house so they move elsewhere... there are a lot of humane alternatives before contacting any rat men! Kayleigh is quite right to advise against the poison - cats, foxes, dogs, etc.
Good luck, and keep us informed!
