I haven't experienced particularly bad customer service, but you need to be careful which inserts you buy..

I can't shed light on all the Heuer inserts, but here are my findings..
it seems that they are slightly confused between the 1163 and 11630...

11630 GMT.. These are the wrong size.. They will fit, but they aren't wide enough, so you get a gap between insert and glass. I think they have been sized for a 1163.

The only insert for the 11630 that is the correct size is the min-hour 'flat' with bezel pip.
I did buy a tachy version, but again, same issue as the Gmt above.

I say the min-hr fits.. Well not exactly.. You might need to lightly sand the outer edge.

I did offer my assistance with correct measurements for all models, but I didn't get a response.

Stewart