Problems with delivery service configuration

[Santscho]

Hello everyone. I want to configure carrier selection but something goes wrong. i will try to explain what i want to achieve.

 

I have two delivery options:

1. There are products which can be delivered in an envelope. These are not very heavy and can be sent with the normal letter post (cheaper)
2. The other products get delivered by packet post (more expensive) if they are heavy

So I've created two products.

1. Product 1: 0.1 kg weight (this would be sent by letter post)
2. Product 2: 1.5 kg weight (this would be sent by packet post)

And there are now two carrier

1. Letter post (0.0kg to 0.5kg)
2. Packet post (0.5kg to 30kg)

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Now, i put only the light product in the shopping cart. Only carrier 1 should be selectable when checking out! Because it's only 0.1 kg and carrier one has price definition for 0.0kg to 0.5kg. BUT prestashop offers carrier 2 (packet post) as well! the customer should not see carrier 2 option.

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Now, i put 3 pcs of the heavy product in the shopping cart. By logic, carrier 1 for letter post should be disabled now! because the weight of my products in total exceed the allowed 0.5kg for carrier 1 (letter post). 1 light product (0.1kg) + 3 heavy products (3x1.5kg) = 4.6kg total weight.

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How can this problem be solved? Thanks for ideas in advance!

Edited September 3, 2014 by Santscho (see edit history)