www.Isocialsearch.com review: All their followers disappeared and the seller hasn't warned me about it

I have purchased 7, 000 followers in Instagram. I have paid to www.Isocialsearch.com. I got these followers with one week delay. And after 10 days I noticed that all followers started disappear. I contacted the customer services and asked what has happened with my followers. But the rep responded that these followers didn’t mean to stay for long period of time. It was ok that they disappeared. So, I simply wasted money for nothing.