Its not my plugin but I would like to help you if I can.
The plugin does not support what you want out of the box. However you can override its partial and change the page title to refer to a variable, say $this->page['currentProduct'], that you have set in your own product component. You could append the page_title with the product name for example. I hope that is what you were trying to do.
The approach mentioned by Abbas will work but first you need to make a little change to seo extension component classes. For example, in \anandpatel\seoextension\components\CmsPage.php just change the method from onRun() to onRender().
Then the following code will work fine:
title = "Product"
url = "/products/:slug"
layout = "default"
$this->page->title = $product->name;
Is there any additional information about this issue? I am having a similar problem with Rainlab blog categories not setting the SEO and page titles correctly. While the above fixes may work, modifying the core plugin files is not a good solution.