Can you exchange these items in my account and decrease the aditional value from my credits?
They won;t be able to make those changes.
The best option is to request a refund (not guaranteed for mistaken purchases) then purchase the HTML version separately.
Just in case -you do realise that using HTML that the site will not be dynamic or CMS.
Therefore every time you modify a property/travel you will need to edit the file and upload it via FTP to make the change. For each time you want to add a new item you will need to create a whole new page and modify all relevant links to it from other pages in the site - it’s a big big job.