As I mentioned yesterday, you should include customer support in your product's use cases. You should include in product requirements constraints on these use cases. Some constraints will likely specify the maximum amount of time and effort it should take a user to carry out the use cases. The amount of time and effort should encompass the user's possibly resorting to contacting customer support.
Consequently, the corresponding tests your team creates for your product should also encompass customer support. Lay out key usage scenarios that are likely to stimulate the user's need for customer support and walk through not just the direct usage of the product, but also the support calls the customer will make.