prestashop webservice assistance

hello i have done a script to communicate with prestashp webservice, i am able to read data well, all is configured correctly and running, and i have done several functions to read different data sets right now i am having an internal 500 server error when adding the product (error by the webservice, not the server running the script) i need help with that (I am an experienced developer but not so much with the website) so also need some help when adding products, to automatically create the categories and such basically the summary of all tasks on this project are: - when a product is bought, call our 3rd party api sending the invoice, receipt, & customer details (need help setting up the 'hook' for this) - read data from our api to add new products or update existing products & quantities (i have created the function to update quantities, so just need to insert if not exist, or update if exist) the project is a bit short on time, need to finalize this stuff ASAP , ideally within 1-2 days ; willing to pay extra for that NOTE: post a custom message when bidding, bids with template texts will be ignored