This qualitative study explores how dark patterns are used in the booking interface of online travel agency (OTA) platforms. Focusing on the accommodation section, the research applies artefact analysis based on Persuasive System Design (PSD) framework to examine how these patterns appear at different stages of the booking process. Three major OTA platforms were analyzed through systematic observation of their mobile applications. Findings show that all platforms use a mix of dark patterns, but with varying emphasis: Agoda relied heavily on urgency and scarcity, Hotels made frequent use of forces actions and Booking displayed a broad combination of manipulative strategies. Logged-in views often contained more personalized elements, such as the user's name, membership level and exclusive offers, while logged-out views required more steps to access certain benefits. The results reveal that dark patterns are integrated into every stage of the booking process, from the home page to the payment screen. These findings raise important questions about transparency, user autonomy, and ethical design practices in the travel booking industry.