Find the answer to your question
I am seeing the value "PromotionalShippingMethod" as the ShippingServiceSelected and as a ShippingServiceOption.
What does this mean, and how should it be handled?
Sellers can specify a Promotional shipping rule in their My eBay: Combined Payments and Shipping Discounts settings.
This rule applies to combined payments only.
It does not apply to the checkout of single item purchases.
The PromotionalShippingMethod shipping service represents the promotional rule.