
Flag - you are owed, at the very least - a partial refund.
Supposing that you did not consent to the extension (obvious that you didn't) you should have the right to reject the order and demand a full refund.
You paid them to deliver by a certain deadline and their failure to do so is a violation of their implied contractual agreement with you.
They will take the full price from you regardless but will surely devastate the writer with penalties.
Where legitimate companies are concerned, it certainly is not a "win-win" situation.
The writer is, obviously, irresponsible and if the company is above board, it will not hesitate to offer the client a partial refund and fire the writer.
Writers who cannot respect deadlines or give adequate notice of their possible inability to deliver by the stipulated date have no place in this industry.