Returning a lease van

What happens if I have exceeded my annual mileage limit? Can I return a lease van early? Can I extend my lease contract? Can I dispute end-of-lease charges? Do I get my initial payment back at the end of a van lease? How much fuel does my lease van need when it's returned? What happens to lease vans when they're returned? What documentation will I need when my lease van is collected? If I damage my lease van, will I have to pay? How do I arrange collection of my lease van? Can I return my lease van during COVID-19?