You can install our site as a web app on your iOS device by utilizing the Add to Home Screen feature in Safari. Please see this thread for more details on this.
Note: This feature may not be available in some browsers.
If the delivery acceptance was done prior to delivery then both Tesla and the OP are at fault. That should never happen for all the reasons stated above and its wrong no matter what the reason was.
Then again, if that comment "I'll never buy from you again!" comes after unreasonable behavior and/or serious mistakes by the seller, maybe the seller would be better off (morally too) fixing things - the relationship included - rather than using it as an exit.