I am continually surprised at the number of suppliers who will promise anything to get shelf space or their preferred terms and then shrug their shoulders when it comes time to deliver upon their commitments.
If you know, or even suspect, you will not be able to meet a commitment, whether a delivery date, a production quantity, a certain level of promotional support or a particular differentiated product offer, don’t create the expectation in the first place.
In reality, stuff happens; if you do need to fall back, explain and clean it up. Makers who consistently fail to keep their word only create distrust and frustration on the part of the retailer. The retailer may not be willing to jeopardize their sales budget by taking immediate action, but they do not forget, and sooner or later, the maker who is unable to keep its word will find itself without customers. A big reason for this is that retailers talk to each other.