correct issue other on my site

You need to help me with code issues (mpdf is not working perfectly, calculations are not working entirely...) and other stuff in order for the site to work. Code is complex (some would say) so in order to get into code you will need to spend a couple of hours or more. I expect you to be available for 15-20 hours work next week and to have a sufficient good overview of sitecode and method used so I dont need to explain issue / code in various assignments more than once.