Van der Valk in Tiel

I have been a regular customer at Van der Valk for many years.
With this particular Van der Valk, my friends and I came in unannounced on a Sunday @ around 18.30.
The restaurant was maybe 20 percent full.
However, we were first told by the attending person that there were enough reservations for the evening so we couldn't eat.
After this, we were told we could only eat if we were hotel guests. I offered to book a room (because we were very hungry). This was not accepted.
I then proceeded to ask for the manager. The manager said the staff wanted to go home early (it was 18.30!) and therefore they couldn't have us. After this, the manager came up with at least two more completely random excuses. Long story short, they didn't want to make money for some unexplained reason? Flabbergasted, I decided to file an official complaint through Van der Valk online. I have reminded them about this complaint for at least 5 times (!). Still today, I am awaiting their response.