This is a complex answer. The simple truth is that if the recipient party is inside a country that is compliant with the DMCA laws set up in the US, they have to, or are by law required to take action. This could be either a failure notification or a successful notification. With your artwork being removed. If they do neither, then you can either send them a repeat notice in order to remind them of their failure to do something, or make provisions to hire a lawyer (in the country of their offices) to take the necessary steps to get the situation resolved. This part can be costly and may not have  quite or successful outcome.

Other options would be to contact the companies directly, contact the copyright offices of the country of the company that is refusing to participate in the legal takedown. That list can be found here!

At the end of the day, the data you have sent via the Artistic License form has been sent to you as a back-up copy, so there is no reason to think you need to send it via the form again. You will have the PDF Takedown notice and the necessary email addresses, so you can simply keep sending the notice as often as you wish.

Another option is to shame them in public, by making comments and claims via Twitter or Facebook about their unwillingness to do something about illegal activity on their stores. This can be a little risky as it could mean complaints being filed against you.