iphone silent button is not working at any time.

mere iphone xr me silent button m dikkat h and service center wale khte h ki ye software issue h

and usme charging bhi slow ho rhi h but mai aaj apna iphone subbmit krake aaya hu and unhone mujhse bola h ki agr koi issue nahi mila to humm apka phone wapas kr denge aisa kyu?