I run a web hosting service and have lots of experience dealing with site cleanup.
I'm assuming this is a Wordpress site, which is the most common, but my bid covers any site of that nature. E-commerce sites are more expensive due to extra complexity and testing.
Part of my task is to update Wordpress and all plugins.
There's a chance a plugin will misbehave or that a design issue will pop up due to the updates.
This will need to be addressed by a designer/developer and falls outside the scope of this bid.
I advise that you delete any unused plugins, once the sites are clean and secure.
To do the job, I will need the following information:
Domain(s) affected.
Hosting panel(s) login/password.
Wordpress admin login/password.
SSH admin/password (If available)