I've used Raza.com to call Kathmandu, both landline and mobile #s, and so far I don't have bad experience. Their call quality is excellent, and call rate is reasonable.
I messaged their customer service back when Nepal was experiencing crisis due to the massive earthquakes asking them if they would offer free calls to Nepal. This was when Viber and Skype were offering free calls to Nepal. Raza.com was not forthcoming to offer any free calls, and that the end to that. They are a business company, so we can't feel bad for that.
If they have really cheated you then you can contact BBB or some consumer organization with the proof.