Are you sure it is shave ready? Did they actually one the razor, and do a shave test?

ideally you want to shave with the new razor, before stropping, so that you have the experience of a blade that is ready for shaving.

Can you elaborate on how the shave was bad? Irritation? Cuts? Not close?
How many passes did you do? Did you go just with the grain, or did you also do across and against the grain?

I've never used a shavette, but I've read that the angle with a straight is much lower, 30 degrees with the grain, less when against (5 degrees? I do one spine width) and across the grain (10-15 degrees?).