Coupon code error

Hello, I’m utterly confused and uncertain of this feature after this.
Recently, I had a customer place an order with items from both Vendor A and Vendor B. Vendor A provided a coupon code, which I set up to apply only to their products. However, when the order was submitted, the discount was incorrectly applied to Vendor B’s items as well. I then had to go in and manually correct everything, which essentially made the coupon code useless.

Why, or how would this happen if specified to only work on specific products?

Hello

Please clarify, are you talking about coupon from addon “Gift certificates” or are you talking about a coupon created in the promotion module?

Best regards
Robert

This was a coupon code I created in the promotions module.

It might be worth sharing your promotion steps so it is easier to get help, such as the Conditions and Bonuses

Gladly!
Created new cart promotion, conditions: coupon code, Once per customer, added only products in Vendor A’s inventory.
Bonuses; order discount by fixed amount.

I don’t use MultiVendor so I’m not sure what options you have but in the standard version, you can use “Discount on products” or “Discount on all products in categories” as the bonus, that way only the items/categories specified will have the discount applied to them. This might work for you if Vendor A and Vendor B are selling different products