Is working as a sales representative for a tourism company that sells hotel nights in five-star resorts permissible (halal)? And would I be considered complicit in any deception if the company does not fulfill its promises to customers?

If the question is about the ruling on contracts for selling or renting hotel rooms for a specific period, then working in this field is conditional on you not knowing, or not having a strong suspicion, that the renter will use them for something forbidden by Sharia. If you know, or have a strong suspicion, that they will commit reprehensible acts, then it is not permissible for you to rent to them, as that would be assisting in sin, according to the Almighty's saying: "And do not cooperate in sin and aggression." As for the company's failure to fulfill the contract with the renter, if you are a representative of the company and a trustworthy agent, and you have not been negligent or deceived the renter, then you are not sinful if the company breaks its promise. However, if you know that the company does not fulfill its contracts and you deceive the renter, then you are complicit in the sin.