Why acquirers treat travel as high risk
The core issue is deferred delivery. A customer pays in January for a September holiday. If the agency fails in between, the card schemes make the acquirer refund those customers. Acquirers therefore price travel against your forward-booking exposure, not your current turnover.
Seasonality makes it worse. A summer-heavy booking pattern means chargeback exposure peaks exactly when cash flow is tightest. Add in third-party suppliers you do not control, airlines, hotels, ground handlers, and underwriters see a chain of failure points between the payment and the delivered service.
None of this means your agency is a bad business. It means the application has to answer these structural questions directly rather than hoping the underwriter overlooks them.