Canada Post Shipping really works on CS-CART?

Spent a lot time to set up Canada Post real time shipping but it does not work.

And I wondered, for each product, there is only “weight” for you to fill out, but no MEASUREMENT LIKE LENGHT, WIDTH, DEPTH ----how can Canada Post calculate shipping fee? Just based on weight is not right.

Tried Interspire and it links to Canada Post in a second ----but the problem is: $10 for shipping one item, and $150 if buyers choose buying 15 ---- we won’t ship each item individually, just put them in a big box.

Is there anyone setting up Canada Post succesfully? Really want to choose CS-CART but…