I cancelled an order and the customer won’t stop messaging me and trying to reorder.

She had been messaging me for months about a custom item that takes a month to make. She asked me repeatedly what the turn around time was and how long it would take to get to her, as well as the cost. She asked these questions over and over and I was very patient and answered her every time. Yesterday she says she’s ready to order but needs the item at her door in two weeks. I told her that was impossible and she ordered the item anyway. I messaged her telling her i was cancelling the order because i wouldn’t be able to get it to her in time. She said she’s willing to pay to rush it, and I explain to her it’s not a matter of money, I just can’t get it to her that fast. She asked me who else sold this item.... I’m so over this customer. She then messaged me a couple times asking why her order was cancelled (I’m beginning to think she’s a troll or someone with short term memory problems). I explained again. She’s started messaging me today again saying she wants the item and asking how much it costs!! I feel like I’m in a psychological experiment. Is there any way to block a person from interacting with your shop? She has also said she will just place another order if I don’t respond.