How long does an ACT essay rescore take?

I sent off a letter to the ACT asking for my essay to be rescored two weeks ago. However, I haven't seen any change in results, or any indication that the request is being processed or has even been received.

Am I supposed to receive some sort of indication that the request was received? How long will it be before I hear back from them? How will they notify me if the score changes?

You should get a letter with your results within one to three weeks if it's already been two weeks since you sent in your request. Here's a quote from the ACT:

"ACT will inform you by letter of the results of the hand-scoring about 3–5 weeks after receiving your request. If a scoring error is discovered, your scores will be changed and corrected reports will be released to you and all previous score recipients at no charge. Your hand-scoring fee will also be refunded."