Hi Dieter, welcome to AAM.
Firstly before I say anything, which option appeals to you most?
Secondly, to give advice on which option to take you would need to consider some things.
-Have you any children ? (you may need access to money soon for college, school, medical costs!)
-Have you an emergency fund set aside in case of an unforeseen expense (losing job etc)
-How safe is your job (affects your ability to repay mortgage etc)
You are in a good position as you have several options, some which you have highlighted.
Heres another suggestion for you to consider (which is to be taken on its merits, I have very little to go by on information, Its just based on the limited info you have provided) -
You could use some of your savings to throw off a lump sum off your mortgage. Increase your revised Mortgage payments to €1100 per month and save the €900 you mentioned. At the moment Halifax offer 7% for monthly contributions. This coupled with lower interest rates on mortgages would make it financially worthwhile considering this option.
I suppose if your only goal is to pay off your mortgage then option 3 is the one you should take. Please note, this is not necessarily the most cost efficient way, simply the quickest way that can be calculated with the figures we have available.