After I was so exited being a week not ripped off or overcharged I got the "help" from Losmen Sibayak to find transportation to my next destination Kutacane and they disappointed me terribly.
They stopped a minibus for me with only one seat left. I asked the driver for the price. He wanted rp 20000, on which I agreed. Suddenly the son, sent by his mom (the manager) showed up and started talking with the driver, after which he demanded rp 35000. He didn't want to take me anymore. What a fantastic help !
I walked away and a little further, close to the market, a boy was making a job out of stopping buses (it's very difficult to find out which passing bus you need) for rp 1000!
I discussed this with other travellers and many said being offered tickets by Losmen Sibayak for (relatively) ridiculous amounts.
So watch out, and buy your tickets somewhere else !
A very funny - because it's so obvious -, but sneaky trick is the donation book.
While a donation of about Rp 3000 ($0,40) each is considered generous, the amounts written by previous donors in the book show Rp 20000, Rp 50000 and so on.
If you look closely you see that they added at least one 0 !