Affiliates Sharing Link

Hi there

I have installed and tested AddThis extension as a way for my affiliates to share their unique link on social media and other channels. However, I’m having a few issues:
– Is there a way to customise the image and text displayed in the links shared on Facebook? At the moment is showing a link with the heading ‘Page Not Found’
– The link being shared includes a reference in the URL for a page that does not exist. E.g.: instead of sharing the links www.mypage.com/?affiliate=01, it shares something like www.mypage.com/page_id=10&affilate=01, thus taking referrals to a non existing destination page. Is there a way to remove that part of the URL that creates the trouble?

Basically, I’d like my affiliates to be able to share their unique links with the click of a button, without asking them to copy-paste that URL

Thanks