I have a wtva,folding step thru (vtuvia) .bought in June 2021 from amazon and I had a cutting out problem.Comtacted the seller at 4:00 pm and at 6:15 pm, the same day was contacted back by the seller. Told him of my problem and was sent a new controller and battery ,free of charge within 4 days. Was told to send the other battery to have it checked out .free shipping and the battery came back to me . Now I have 2 batteries. Could not stop a rear brake noise so I was sent a new caliper .200 miles and I am real happy with my $1299.00 electric bike .This is the best customer service I have ever had.