Hey mate, just double check they are a true 2/3 piece rim first. Then check if the dish section is chrome (doubt it if they are real 2 piece), stainless or polished alloy. Alloy would be the easiest to repair IMO.
My boss used to part own 'the wheel factory' and when they closed they still did alot of wheel repairs outta jax fyshwick. He has since sold most of the equipment and only has a large lathe left for en-larging centre bore holes.
Wicked wheels I have seen repair a BMW alloy in the flesh, had a deep section of gutter rash which was filled with a special bog/filler, filed back and the whole rim resprayed, all in the back of a van. Have heard good and bad but that's the same with any business
There is also I newish bloke called MAG! Wheel repairs, he welds cracked rims and flat spots, not sure what else he does or if he can help u out, his in fyshwick.
If you pull apart the rims any panel shop can blast and spray your centres.
Most wheel repairs are expensive and cost as much as the cost of a new rim, if the wheels are no longer available or are custom made then that's when u need these peoples services. Maybe if it's just the one with rash it might be worth looking for a 5th wheel. Maybe check eBay or post a pic with brand, size, width, offset , pcd etc and I can see if they are still available?