noises while calling and recording

Good afternoon,

I am writing you because I am desperated. I was now 3 times in your apple atore in Wallisellen (CH) in the Glattzentrum.

I told them 3 times the same issue , i spend a lot of hours in the store.

My device is still making noises while I am recording or speaking with other persons.

They cant fic it so the store manager offered me to switch to an iphone 8. But he wanted 400 CHF for the swap.

Currently I am working in Portugal. It is a big to travel every time to switzerland and instead of seeing my family and friends I spend my time in the apple store and get no answer. The shop manager itself seated me and left for about 40 min until he returned. I am a very patient person but thats too much.

At this moment i regret the switch to apple. Please can you help me?