why is my monthly limit not resetting?

I started my Plus account back in May. So far I've received 996 total responses since I started the account. It is now July 28th and I got an email saying I’ve used up half my allowed responses and it won’t reset to zero until August 22nd. If my monthly limit is 1,000, why isn’t the count resetting until  three months after I started the account? Really frustrated to receive this email as the annual price is no small investment and I should be getting my full 1,000 responses for each month.