Insurance company gave me 1 day to find a car before they take the courtesy car back.

So I had a no fault accident a few weeks ago and it took a few weeks for the claim to process. My car was written off (it’s a banger anyways) and wasn’t deemed worth it to fix so was written off as a Cat S. I was supposed to be paid out on the 5th of June, and I got paid out today (15th June) because they kept delaying the processing of the payment for no reason.
Now they have said they will take the courtesy car back tomorrow and won’t let me extend the date as it was already extended once from last week as I still had not received payment. I still own the Cat S car, but repairing it and getting MOT redone etc, takes a long time. And to be honest I just wanted to sell it on myself for more money as I bought it back off the company that wrote it off for only £60. I can scrap it for more than that.
The plan was always to buy a new car, but I can’t go look for and buy a new car without a car. I work full time and commute everyday, so how is just ONE day even a reasonable time to give someone to buy a new car. What are my rights and what can I do legally? The courtesy car company won’t extend it as they have already done so once but it was the company Nationwide that took so long for me to get my payment.