To be honest, I'm suprised you've received any funding. You're a company that increases Twitter and Instagram followers. This is a deeply dodgy, largely unproven and mostly saturated market and you're charging prices that'll leave you out of pocket. No way are you worth $600,000. There's no way you can get enough customers.
Unless the followers are actually relevant, interested and verified-as-human-beings accounts. If that's the case then $600k is a fraction of what the company could be worth.
There's a lot of 'ponzi scheme' follower increasing apps and systems ($5 for 5,000 followers, 'team followback', etc), where people sign up to get more followers by automatically following other people who join the scheme, but the number of good applications that can find people who would genuinely be interested in hearing your message is, essentially, zero. There is an opportunity in the space but the problem is a hell of lot harder to solve in a worthwhile way than just increasing the vanity metric of "# of followers".