Unexpected Supplement paid

I am writing regarding the reservation n. 129780919 and n.129870866 made with Dertour.
Once arrived at the Hotel we have been charged of 100euros per night per room for a supplement, without any notice fron Dertour agency or hotel itself. We have booked and paid to Dertour months ago so we didn't have to pay any supplement.
A Dertour agent called Mahmoud Saad came to the hotel where we were staying and signed a complain form with us, which states that we have to be refunded.
We paid 400euros of supplement for two nights and two rooms and the third night (we booked 3nights with Dertour) has been canceled, so we had to book from Booking the last night (287,00euros)
We ask to be refunded of the supplement and the night Dertour canceled.
I attach here the receipts of the supplement, the complain form signed from the Dertour Agent and a proof of the night booked from Booking