Driveway Stopped Responding After High Offer For My SUV

I decided to sell my SUV to this company because they seemed very interested at first. We started discussing the details, and they asked for official documents like my license, pictures of the car, and some other information. Honestly, their offer was higher than many others, so I felt confident about choosing them. However, after I decided to go with them, everything changed. The representative stopped answering my inquiries. I sent follow-up emails and made phone calls, but there was no response, didn't understand what went wrong or why they suddenly lost interest after showing so much enthusiasm initially, submitted all the required documents, and I was ready to finalize the sale. They’re giving me no clue whether the deal is still on or if I need to start looking for another buyer. The lack of communication from their end is highly unprofessional…