Setup 1.16.1.19 , default prestashop Shipping , no add on module.
1) We have products which are packed in glass bottles and need special packing. hence Additional shipping fees (for a single item) in the products -> shipping tab "10" is added per item.
2) Shipping slabs as per weight are set eg. 50 for 0.0000001 to <= 0.500 , 100 for <0.500 to <= 1.000 and so on
3) Free Shipping over 800 cart value.
Issue :-
1) when the Cart value hits the threshold of 800, the Shipping becomes Free. This is correct. however
2) the Additional Shipping of 10 on any such product also becomes 0 - This is incorrect.
example :-
Cart has Product A * 3 @ 40 Rs , Product B * 1 @ 70 Rs, Product C * 5 @ 100 Rs
Over All weight is 0.0000001 to <= 0.500 That is 50 Rs shipping
Only Product A and Product B need Special Packing. Hence Additional Shipping fee of 10 per product quantity is charged.
Product A* 3 = 120Rs + 30 Additional fees
Product B * 1 = 70Rs + 10 Additional Fees
Product C * 5 = 500Rs + No special packing No Additional Fees
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Products 690 ( Threshold of 800 not met )
Shipping 50 + Additional Fees 40 = 90 Shipping Charges
Total 780
This is Correct
Now when the customer adds More products and hits the free shipping threshold of 800
Addtional Product A * 3 = 120Rs + 30 Additional fees
Now the Cart Looks like :-
Product A * 6 = 240 Rs + 60 Additional fees
Product B * 1 = 70 Rs + 10 Additional Fees
Product C * 5 = 500 Rs + No special packing No Additional Fees
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Products 810 ( Threshold of 800 free shipping is met )
Shipping 0 + Additional Fees 0 = 0 Shipping Charges
Total 810
This is NOT Correct
What We Expect as per Policy :-
Products 810 ( Threshold of 800 free shipping is met )
Shipping 0
Additional Fees 70
Total 880