Get rid of the hero image.
Get rid of the Contact, Welcome and About us boxes.
Add a navigation system.
Move the contact number into the header
Add full contact details to the footer.
Bin the twitter thing (you don't have a twitter page)
On the product categories condense the intro and remove the video as it pushes the products below the fold.
The 'Enquire Now' buttons don't work.
Some of the product pages need a lot more info including the tech spec pdf. There is a huge chunk of whitespace on the right of some products which causes the list lines to wrap. This is because of the awful bootstrap grid you are using. Example:
https://dan-packaging-machinery.co.uk/pages/capella-flow-wrap-machine
A number of product are similar and would be better displayed as variants. The Reply EVO machines for example.
Add an enquiry form to every page.
Bin the blog - it's adds no value.
The ONLY reason why anyone will ever be on the site is because they want a machine. So your job it to lead them to the machine and then market that machine.
Using shopify is a bad move. You would have been far better off with a dedicated site. Just because you had a bad experience with a developer doesn't mean they are all the same.