Best thing to do is just let them know you don't need to refill any medications, but ask for a call back number.  Then, if you don't want to get any more calls, block the number.

this is a customer service center calling to see if you want to order more meds - if you've ordered from an online overseas pharmacy, this is who is calling you - not spam - you gave them your number... i just ignore them until I am ready to reorder (online of course)

I never got my meds did u?

What happens is if you have even subscribed to an affiliate merchant/website which may have nothing to do with meds at all. These sites share a little or much of your information with all their affiliates. Not financial info, but emails and #'s. They get a penny, if that per contact, but that's how it works. Usually in the Terms of Service we all check the box and move on as fast as we can. In the finest of print they reveal their methods. It could be a Hardware Store website, clothing or even tires for a truck. Somehow these sites are often affiliated not for any other reason than money. Enough pennies add up over time. They can also get your # with just a name, or an email address. I get at least 4-5 calls per day from online merchants. I just click off the call  when they ring.

What I've done is answer the call and just don't say anything. This makes them angry.  When I started doing this, they would call back immediately and I would do the same. After a few times of Doing this, my calls have reduced by 90%.