Final answer:
The company with an AWS Enterprise Support plan should use their current plan for quick and efficient guidance on billing and account inquiries, as it provides the most comprehensive and personalized support compared to other options.
Step-by-step explanation:
If a company already has an AWS Enterprise Support plan and is seeking quick and efficient guidance with their billing and account inquiries, they should utilize the resources available within their current support plan, which is option 4, AWS Enterprise Support. The Enterprise Support plan offers the highest level of resources, including 24/7 access to senior cloud support engineers and a Technical Account Manager (TAM), who can provide personalized support. With this level of support, the company will receive one-on-one, fast-response support for their billing and account issues.
Options such as AWS Basic Support, AWS Developer Support, and AWS Business Support are not as comprehensive or personalised as the Enterprise Support. Among these, Basic Support offers customer service and documentation, Developer Support is geared towards early development and testing environments, and Business Support is for production environments with business-critical dependencies, however, none offer as direct or as high-touch support compared to Enterprise Support.