Track product ecommerce data thats not present on thank you page
I am working on PPC'ing a site that does not have product data on thank you page. When a user lands on thank you page it just shows the transaction reference number. Obviously the ideal solution is to ask client to ask developers to transfer sales data to thank you page but thats not going to happen in near future.
The current check journey is like this: Review Basket >>3rd party payment>>Thank you page
Google Tag Manager is installed. I wanted to explore is whether it's possible to scrape the product and price data on review basket and pass the data to GA when someone clicks the pay now button (effectivly when they leave the page by clicking paynow). So in a nutshell before they hit 3rd party payment site the product data is transfered to GA ecommerce tracking as a transaction. I know its not ideal as payments may decline but i can't think of another way.