The spare parts for your Hero Maestro can be bought from any of the after market accessory shop and even if it is not available with the shop, you should wait for the person in the service center to order one as fitting any other would void your warranty as well as the peace of mind of getting a genuine part. The detail about the Honda Activa's body clamp can be confirmed from the person at the service center as he would be knowing the exact difference, if existing, between both of them.