flange problem connecting axle to motor

I have asked the parts prices on this subject before, but I do not know why the malfunction is caused and the masters do not know

my car 2001 206 xt 1.6 16v 110hp auto. gear

My problem is that there is a small aluminum milled part called flange that connects the axle to the motor and it constantly strives and the vehicle is on the road.

So far, I changed the flange 3 times, but they said the result was broken with the last complete axle as well as the end of the change axle.

Is there anyone who has encountered this problem before, or is there anyone who knows why the problem may be caused?

Believe me, I spent a ton of money on this fault and they couldn't fix it, and I thought I would even sell the car for this problem, but I gave up because I love my car and this malfunction happens almost every month so I have to come to a definitive solution now.

I'm waiting for your help

Thanks to everyone in advance ...

They said that the axle I took to the service will change completely with the flange.

I had a small accident right from the owner before me, I think it would have an effect, but when I first bought it, I did not understand such a problem.