Copy write US Lawyer

Hello I have just set up a new prefab home business. We buy prefab homes from a Chinese company and sell them online to clients, we started the business about a month ago. The Chinese company provided us with all the plans, pictures and walk through videos, which they said we could post on our website, However, we were contacted by another company, called Concept Homes, that claims that we are infringing on their copy right material of few of their houses. We wrote them and apologized and quickly and told them we got the marketing material from the Chinese company and removed the houses they claim to be their designs. We have not made any sales yet and nor have we used any of their plans. They have threatened us that they can take us to court if we do not pay $24,000 USD. We explained everything to them and asked if we could resolve the issues with any money exchange, because we are a start up company and we do not have that amount of money. They than agreed to set up a payment plan and demanded that we pay them $3000 as the first payment and $2000 every other month until we finish paying the total cost, otherwise they will come after our assets. We are a registered company in the UK, but we live in the Czech Republic. They are from the USA and they claim they have a company also in Lativa. I feel like this may be a scam, but I checked out the company and they do have a website, but it does not show that it is located in the US or Lativa, however based on their invoice they sent us they are registered in Lativa. Because they have been hashing us with legal threats we paid them $3000 USD. I am not sure if this was the right thing for use to do? Can you help us to get these people off our backs and help us resolve this, I am not sure if you know a lot about Copy Right law. But if you do can you help us? Apply tot his job