X2
Take it back and make them fix it even if they have to use a different tire or two.
A tire need 3 oz isn't your problem and I am positive you didn't ask for a hard to balance tire when you bought them.
I have to make my shop rebalance tires all the time when I get them changed.
So much in fact that I'm going to look around for a different shop.
Point is, tire balancer people don't make a lot of money so the quality of the job is often in relationship to that.