The sad reality appears to be that for Thailand (at the moment) getting the medications outside Thailand and bringing them back always works, but for import by mail it's luck of the draw - some shipments get through and some get seized.
REDEMPTION does not ship to Thailand because to the need to smuggle the medications in, however I suggest you join the Facebook group "Hepatitis C treatment w/o borders" and ask there. This group contains people familiar with the challenges in Thailand and ways to get medication into the country.
On the good news front Thailand is participating in the Pharco/DNDi trials of Sofosbuvir + Ravidasvir. Without boring you with too many details the expected outcome of this trial is a pan-genotypic treatment where the product has Data Exclusivity owned by "generic friendly consortium". In the event Thailand issued a compulsory licence on Sofosbuvir it could be registered in Thailand and the target price is $300/12 weeks. Best case is that it's still a year away, but it's in the pipeline.