I am having a hard time picturing your location of the problem. Do you
know how the original foundation was done? Is it deep enough, thick
enough? If it is and you just have some settling, I would just patch
it. If the foundation is too shallow and/or too thin, this will be an
ongoing issue. You can fix it yourself if you are so inclined (I am
assuming a 3 foot deep foundation around the garage). There are some
good books on repairing foundations (ie Fine Homebuilding).