Editing the HTML site

There's a website. Very old. Each page of the site is a separate HTML file. It's 354 files. You need to replace the text in the footer, in sidebars in each file and change the logo in the hat. There's a logo. All changes must be made manually on the site. So. Automatic replacements have been tried - not everything replaces, or knocks down the layout. We work gradually: we made 10-20 files – we paid for it, we did more – we paid for it and so on. For one file 10-15 rubles.