@Idalecio1 You already paid for the whole house? What does that mean? I assume you already paid for what the host charges to house one guest. And you also likely got a discount as you booked it for 3 months.
I don't know how many children you have staying, but 1000 doesn't sound at all unreasonable for 2 extra people for 3 weeks. And charging extra doesn't just cover utilities, bedding, towels, etc. The more people,the more general wear and tear on the house, and the more potential for someone to damage something.