Jimny mud flap fixings

I have had this issue before - so I went slow, careful, applied anti seize.
I just removed the front mud flaps on my daughters jimny, there are three bolts. Apart from the 10mm self tapping bolt, there are two 8mm bolts, which fix into some kind of rubber fixing with a metal sleeve, which as you tighten it, it expands in the cavity and makes the flaps secure.
I guess this is because they use existing holes which are for the push fastenings, so have a cavity behind them.
I have never successfully been able to remove these without damaging them, no matter how carefully I try!!

Firstly, what's the technique, if there is one?
Secondly, is there a part number for the genuine replacement parts, when I do a google search, it just comes up with all manner of self tapping screws?

The technique is to get them off! Usually the screw is damaged by corrosion and the female part of the fitting rotates as you try and remove them. If you got them off without damaging the body parts, well done. As to replacements, either a specialist nut and bolt merchant or a google search or something from the Rawlplug range would probably solve your problem. Asking your local Suzuki dealer will depend on whether the parts manager has a PhD in obscure fixings made from unobtanium.

Roger