I need quick fix regarding pagination on my shopify page

General information for the website: we sell babyequipment
Description of requirements/features: I was told to fix this issue by my SEO company and have translated their message to english. Im not good with HTML so the translation might be a bit strange.


Pagination

On productpages with more than 16 products, there will be created more than one page. Page 1-2-3 etc.. The implementation of rel=prev/next and rel=canonical has been made to avoid "pagination" but it has not been done correct. rel=prev on ect. page 2 points back to the category mainadress with a pagination parameter.

besides this there is a sorting parameter in rel=prev/next.

This can make google choose to ignore the rel=prev/next annotation and the value we can gain from having this annotation will be lost. These annotations will send goole on to the paginationpages with the sorting parameters that has rel=canonical to other pages. This is a waste of work for the servers and the search engines/google and can result in lower rankings

So to sum up

Rel=prev/next should point to the previous/next page and both without filter/sorting parameters


On this page http://mamamilla.dk/collections/mere-til-baby?page=2
It has these values
REL=CANONICAL: http://mamamilla.dk/collections/mere-til-baby?page=2 (is correct)
REL=PREV: http://mamamilla.dk/collections/mere-til-baby?page=1 (is wrong)
REL=PREV should be here http://mamamilla.dk/collections/mere-til-baby.

If you sort a category the REL=PREV/NEXT is set up wrong as the pages sorting parameter is included

An example is this: http://mamamilla.dk/collections/mere-til-baby?sort_by=title-descending, with the sorting ”Alphabetically: Z-A”, has the following values:
REL=CANONICAL: http://mamamilla.dk/collections/mere-til-baby (is correct)
REL=NEXT: http://mamamilla.dk/collections/mere-til-baby?page=2&sort_by=title-ascending (is set wrong)
REL=NEXT should be: http://mamamilla.dk/collections/mere-til-baby?page=2. without the sorting paramenters.

Besides telling the search engines that the pagination-pages are one long "chain" the total value of these pages added to all pages in the "chain" Duplicate content as a result of parameter adresses, will be handled at the same time with this solution.
Extra notes: