Please send photos and a more detailed write up of what has happened and what the problem is.

Oak veneer is still a hardwood, but there may be veneers out there that are soft but have the oak like appearance...is this what the contractor used ? I'm assuming that the veneer was placed on the face of each tread (step). What i mean about 'face' is that the face is 3/4" thick or so. The face doesn't get no traffic so it should hold up. But yes, more details/pictures are needed