Headset micro volume too low

[YannG]

Hi.
Since the arrival of T4x series that I've sold many times, all my customers using headset have the same problem: The headset micro volume is too low, resulting on remarks from their interlocutors, complaining they can't hear them correctly.
This problem is encountered on T42, T46 & T48 models, with last releases of Plantronics & Sennheiser headsets=.
I made up this information for several months to French distributor, but no feedback from Yealink.
My problem seems to be shared by many other users on this forum.
Question:
Does Yealink will correct it very urgently or do we have to buy other devices from competitors (Aastra, Snom...) where the problem doesn't occur ?
I've many project with hundreds of phone devices, where I can't get with Yealink till this problem will not be corrected.
Thanks for your urgent answer.