beats2 wireless

buzzing noise coming out from beats2 wireless, connect bluetooth to my iphone 6s plus.

it's not all the time, on and off.....

this is my replacement from last year - now Apple wanna charge me $99 to fix it... and 90 days .. which is bS***

what causing the issue? I heard its design defeat ...

I don't think Apple care much about Beats.

Anybody having the same issue ? why causing it ? and how to fix it? appreciate it.