[NOP4.0] and problem with sums of few discounts coupons?

Hi all!
we have problem after make update to NOP 4.0.

We have some discount coupons and don't know why CLients can use X of them and discounts are summed.

Example:
Client receive discount on first order (XX $ assigned to order) + use 5% discount (assigned to part of order)...

Earlier this discount wasn't summed. And he needed to made a choice which he want to used: first or second discount.

We want give him choice use first or second discount, but no both... (we also have free delivery, so this is nice combo but we earn nothing...

I checked and all our discounts have unchecked checkbox "Cumulative with other discounts", if i good understand, discounts summary should work when we enable it? not, when this option is unchecked? Can somebody tell me what i do wrong?

Anybody know another forum, where it's possible to receive any answer?

I need to know, what i make wrong, i don't think nopcommerce team don't give possibility to block many discounts in one order... ?

The discount type "Total sum" adds on top of other discounts, ALWAYS. This is not great for business.

We use category\manufacturer discounts instead, and the store owner will have to add all categories if they want all products to have a discount.

Example:
If a product have a fixed discount for 10$, and a category discount for 5$, the category discount will NOT add on top. If you use total sum, it WILL add on top.


This is at least what i have experienced.