A good brush but unfortunately the styling part detaches

I am loyal for a long time to Denman brushes, having discovered this excellent brand drugstore in London.
I have very thick hair (not curly) and this brush unravels quickly and with a natural effect.
Especially the material is very nice and does not generate static electricity.
In addition it is easy to clean and maintain proper hygiene.
The only drawback is that the red part with the pins can be removed without stopping. She slips a little, about 1 cm every brushing, and we must reject it, which is not easy. After a moment, she is no longer at all.
It would be really great if Denman could solve this problem.