Can't change earpiece volume on Nokia Lumia 630 Dual Sim

[Talha Taher]

I have the Lumia 630 Dual sim. I can't change in call earpiece volume. It shows that I can change the volume but actually nothing happens. In call volume is still too loud. When I plug in a earphone I can change the volume. How can I resolve this issue? This phone came with Windows Phone 8.1 and Lumia Cyan. Since then I got one update and it didn't fix that. Please help.