You are dealing with a Civil Law court not a Common Law court as in Ireland, that means there is no such thing as extenuating circumstances, the letter of the law is applied. Your only defence could have been that you were not driving and that you were able to supply them with the name of the driver. You did not do this, but instead wasted their time with a nonsense appeal, meaning you should probably expect they will have upped the total to the max.... I'd expect the next reminder will be north of €1,000 and possibly as high as twice the original fine, say €1,300.
This is not going to go away, because that is not the Swiss way. If left unpaid it will continue to collect further charges and penalties, of which you will be reminded. Eventually it will be come a criminal matter.