Cera — In 4 months of purchase the shower cabinet fittings are rusting and taps have lost polish colour

It has been only 4 months since I fitted all my cera fittings in my house but I regret to say that you can even go for local brands than going for them.
The spouts have lost colour, some flaking and coming out, some rusting and every time I complain they close it without attending to it.