We rejected the acceptance. The acceptance protocol was not signed by any of the parties.
We withheld the 5% security deposit (he had invoiced us for this) and the installment F) is still outstanding according to the broker and developer contract (due upon completion).
From my point of view (but admittedly not a lawyer) this is not sufficient, because from the file's perspective it does not go beyond a mere failure on your part to meet the deadline. Your witness should confirm that you were there and how the appointment went (i.e., sign the protocol if it is complete, possibly by adding to the pre-printed content). You then make a copy of this and have it certified. This way it remains provable later that the appointment was fruitless.
I think you should formally hand it over with a deadline. Then it’s his turn again. You can also do this politely but firmly and stay in contact.
That’s also how I see the correct procedure. The contractor must be formally notified of the lack of the agreed usability and the fact that the installment F is not yet due. Otherwise, I see him attacking you for your alleged default from his point of view.
Because the electrician suddenly became ill and they therefore cannot connect yet. That was the reason.
*ROTFL* I won’t pay any more bills because my banker is sick :-)