Lime scale and rust is big problem and to get solution, use Anj Secure Scale and Rust remover.
For limescale,
Spray it on surface , wait for 2-3 minutes , just have a gentle rub , clean with water . if the scale is hard then repeat the process for 2-3 times as mentioned above.
For Rust ,
Spray on the surface, rub it for 1-2 minutes and clean with water.