Revamp and Stabilize Corporate WordPress Site

I need an experienced WordPress developer to update my old corporate website, which currently crashes due to outdated plugins and theme incompatibility.

Key Requirements:
- Resolve issues caused by outdated plugins and theme incompatibility
- Preserve existing functionalities: contact forms and user accounts
- Ensure the site is stable and functional post-update

Ideal Skills:
- Proficiency in WordPress development and troubleshooting
- Experience with plugin management and theme compatibility
- Strong problem-solving skills
- Ability to maintain existing functionalities during updates

Please provide examples of similar work done and ensure you have the necessary expertise to handle this project.