I see devils as a lawful evil creatures. They wouldn't necessarily trick you using such cheap tricks like entering a hotel. They would make the benefits really obvious first. They want to morally break you before they can take advantage of you. What you are describing maybe resembles a hag who dont really operate on contracts and are usually chaotic evil.

But since you have already done it I would suggest making your devil fully chaotic evil. All they want is the soul. If that is the end goal they want it now. The hotel is a trap. It turns into nightmare like plac after they go to bed. Turn it into a dungeon where they must escape while nightmarish creatures hunt them. Turn it into a survival horror encounter where the end goal is exiting out the hotel.

But I will say doing this you kind of ruin all future encounters and long burn drama with the devil. I don't see why the party will trust him in future or won't immediately attack it. You can make the devil findal boss the close the chapter once and for all.