Are you being held hostage by a gorilla account that, if they left, would destabilize or even destroy your firm? The threat is very real according to David C. Baker at ReCourses, who quantifies these things. "One half of all firms that lose a client representing at least 35% of their revenue do NOT survive." You might want to get ahead of that.
First principles are the foundational truths from which all other principles or assumptions should flow. Over the last year or so I've been ruminating on the first principles of the Win Without Pitching way of selling.