conflict between customer and seller

i need other peoples opinion on something because this has been on my mind for a while now. if you order from a small business and give them half advance payment, and then you end up not receiving your order when you were supposed to (before eid which is a holiday for muslims), but you still give the person grace and tell them you’ll still accept the order after eid BUT THEN after eid the courier company doesnt even attempt a delivery and then returns the parcel to the business, you complain to the seller about it and they proceed to tell you about how it’s not their fault and that you should be the one to contact the courier and ask them instead of the seller, how would you react? because personally i feel like its not they customer’s responsibility to go out of their way to contact the courier company unless the courier company calls them first for like address and stuff..