I used to use Nusatrip.com to bypass the access issues of booking direct with Indonesian airlines. I have always had trouble EXCEPT with Garuda. Nusatrip changed their credit card verification system so all my cards no longer work. I now book with Tiket.com and actually like it a lot better. Their app is good, their customer service can be accessed via WhatsApp which is nice when you are traveling. I had to whitelist my card with them at one point but my friends and partner had no issues. (Whitelisting it meant e-mailing them a photo of my credit card with my passport in the same frame, unedited.) It's completely safe - my data was never compromised.