TOP GUN 3799 : PROBLEM WITH THE DOPPELCHRONO

Hello,
I'm new to this forum and I hope someone can help me.
I have a 3799 IWC TOP GUN DOPPELCHRONO and the button on the left (that of doppelchrono) doesn't work.
The buttons on the right side start and stop perfectly, but the split function doesn't engage.
The watch is no longer under warranty and I want to know if anyone knows this problem and how much the repair would cost.
Thank you in advance.

Hi Kosk,
The most likely reason is the pusher @ 10 has been knocked bending the internal operating lever. Being bent it won't travel far enough, when you push the pusher, to operate the split mechanisim. This would be repaired as part of a normal complete service of your watch without extra cost.
For prices you need to contact your local AD or service center.
Leo