Need to disallow order when exceeding table rate

hi there guys :)

One of our clients contacted us a couple of nights ago freaking out because someone ordered more than we had defined in table rate, and the shipping went to 0.00(we thought it would stay at the highest rate defined).

The client wants them to have to contact her on orders of 13 units and over. Currently, we're handling all of her shipping through the table rate, and it works good up to 12 units, but we really need it to disable the ability to place the order when exceeding the shipping rate, preferably with text stating what she has in her shipping info page(that they need to call for shipping rates).

If not through the shipping rate, then can we tell the cart to disable orders over x amount of units?

Is there a way to do this?

thanks,
json

Depending on your consist of products, you can specify the max weight of a package and the cart will split the order into 2 or more = package weights.

Would this not be preferable over having to contact the shop owner?