[Help] A dev who can fix bluetooth on "Umidigi Plus E" ?

[Aralas]

Hi to all dev's,

We are a lot who have bought a "Umidigi Plus E". It's a correct phone, but we are facing to a bluetooth issue (unstable). We told the problem a lot of time to Umidigi, but we don't have any update which fix the bluetooth since his release ! Just minor updates. They really don't care about us :-/

There is a dev wo can help us ?

Here's the problem/symptoms :
In a car (for example), we can pair our phone easely. But one or two days later, the phone can't pair again to the bluetooth headset OR the voice don't come from the bluetooth system.

When "connected", we cannot tick "Phone audio" :

But there is a temporarly fix. Here's (works only during 2-3 days ...) :

1) Parameter
2) Application
3) Tap on the three dots (right and top the screen)
4) "Show system process" (thing like this)
5) Tap on "Bluetooth share" or "Bluetooth Shared"
6) Tap on "storage"
7) Delete data & clear cache

We don't know how to stabilize the bluetooth. We don't have any dev

Someone can help us ?

Here is a link to get the rom of our phone : http://community.umidigi.com/forum-128-1.html
Here is a link to our phone specs : http://www.umidigi.com/page-umi_pluse_specification.html

... and seriously ... don't buy Umidigi. They don't care about us !

Thanks in advance to the guy/girl/team who will help us