Where to buy the cheapest tickets from Jakarta to Europe?

Several months ago I was looking for ticket from Jakarta to Amsterdam (round trip) and I would like to share which channels I used and which one turned out to be the best and the cheapest.

1. The Sky Scanner app and website provide a good indication of which airlines are available and have the cheapest tickets, however, not all airlines are included in the app, the ticket prices are not always the cheapest available and the app/website does not always show the real price. I find it pretty annoying to see tickets with low price that actually do not exist or turn out to best hundreds of euros more expensive.

2. I also checked several ticket websites, like worldticketcenter.nl and cheaptickets.com.
However, I did not find any interesting ticket.

3. After that, I also checked tickets on the websites of several airlines, like Singapore Airlines, KLM, Malaysia Airlines, Garuda Indonesia, Etihad, Emirates and Lufthansa.
I found round-trip tickets for less than 900 euros per ticket (July/August) on the Malaysia Airlines website, but when I tried to order them, I got an error. I tried to use different names, different credit cards, but nothing worked (after two days, I gave up).

Finally, I found cheap tickets (below 900 euros for a round trip in July/August) through a local travel agency called Dwijaya Tour, which is located in several malls in Jakarta.