You can rent scooters and other mobility equipment for delivery to Barcelona Port at
www.mobilityequipmenthiredirect.com. Book and pay online...it's very simple.
Yes you can hire a scooter from Cosmo scooter, log in to www.cosmoscooter.com/main-in.html click the English flag and all info on prices will be there, I think they deliver to and collect from the hotel, and there is a returnable deposit of arround €200.+ the day or weekly rate.
Have a nice hol.