Here is the link to a company I have used Walker Mobility:
Orlando wheelchair and scooter rentals-serving all Central Florida attraction areas-Disney, Universal Studios, Sea World, Kissimmee-Walkermobility.com
They are super efficient, have 24/7 answering service, which comes in really handy when your ECV gets flooded in a downpour late on a Saturay night- they were there by 9 AM the next morning with a brand new one. The ECV was ready and waiting at the WL when I arrived and they are always ver pleasant to deal with