[Guest]

Social Media complaining seems to be the way forward. Complain on their facebook page, twitter, anything. Also get names of those who couldn't help you or were rude, and names of those who were kind and mention these on your complaints. Go back to City Hall too, it could be different people there, or even just to "get the names of those I spoke to yesterday" then add (after getting names) that you will be mentioning how rude they were. DLH is a considerable amount more than the other hotels. I presume your €100 was a good will gesture and you will be receiving a refund for your DLH missed night. Don't be fobbed off by them saying you got upgraded to Castle Club, people get upgraded at no extra cost at the discretion of staff.
So sorry you are having this experience