I’m surprised at how many people believe they are; such that senior people do not bother to develop genuine vendor/partner/supplier relationships. Speaking as somebody who has considerable delivery experience from the consultancy side of the fence; I can assure you, when you personally like/respect and value a client, you do put that extra effort in. Whether thats with a deliverable or internally, backing their corner in a staffing or commercial discussion.
Top Tip: Make sure your vendors believe in what you are doing and take the time to build trust and respect, it just takes a little effort; so go on, book a lunch with each of your key partners and share the love… It will almost certainly be worth it, in the long run.