Insta Loan — Don't believe them – the sums are too high

I took loan from the company Insta loan. I immediately informed them that I was on low-income, and the agent promised that the payments would be small. The first payment was about $500. I called to this company and again explained the situation. They told me that the first payment would be such, but later I would pay smaller sums. But it was lie. They continued to charge me for the same amount. I wonder if someone can help me to cancel everything with them. Please, post comments.