I am looking to fly one way from POS (Port of Spain, Trinidad) to PMV (Margarita Island, Venezuela), a route served by Venezuelan airline Conviasa. Yet, www.conviasa.aero (their website) only sells domestic tickets and all the online travel sites I've tried (including Kayak) doesn't seem to offer the POS-PMV flight, but I've seen it in Expertflyer.

Any tips on how to most effectively book this? Really trying to avoid the hassle of going via CCS, and want to get this sorted before booking a flight into POS.

Thanks!