ok. I installed this addon and it seemed like everything was working fine.
However, if I twice the quantity of the checkout, the shipping fee doubles too.
For example, one my products is 400g, which costs about $10 for shippping and if I make the quantity two, it becomes $20.
I checked the shipping rate on the official canada post website and they say 0g~800g is 10$ flat rate.
How do I fix this problem?
Please let me know
Thank you