Not just a Supplier
Customers are fickle. At the big ticket end of the Tech Sector, customers are cruel but pragmatic. Even though you can deliver storage management as well as service desk management, the client gives one of these roles to a rival. The downside of squabbling suppliers is offset by your fear of commercial uncertainty. Nobody wants to upset a mood-swing parent who will quite happily drop you off at the care home if you play up.
But if you can convert clients to fans then this rough treatment evaporates. If the client sees you as a partner whose destiny is entwined with theirs then they are more likely to trust you and confide (read order taking opportunity) in you.
Consider how you can move beyond the role of supplier and show that you have invested in the relationship, and not merely tried to optimise the ratio between what you are obliged to do and the price your client is paying.
If it feels like a negotiation you are indeed a supplier.