Basic upkeep. Apparently a radical proposal.
WordPress, theme and plugin updates; backups with agreed retention and restore checks; availability and key-function checks; a record of the work. Significant changes use staging where available, or an agreed safe update procedure. The fact that you can still open the homepage tells you remarkably little about whether your enquiry form works.
Your “tiny change” still has a size.
An agreed allowance can cover content, layout adjustments, small functionality changes and search-related improvements. Larger work is scoped before it starts. Adding “just” to the beginning of a request does not reduce the implementation. Equally, changing a sentence should not require a procurement exercise. Agree the boundary and use it.
Yes, we can look at the site you neglected.
First comes a review of the setup, access and current condition. Initial repairs, licences and hosting changes are identified separately. Response times and responsibilities are agreed in scope. Supply the access and whatever records exist. “The last guy did something” is useful context for a mystery novel; we will need a little more to maintain the website.