Battery Cable problems of the 2007 Mazda MAZDA6

I have an 07 Mazda6 that I recently had to replace the 2 battery cables going from the positive terminal to the alternator and the fuse box located next to the battery (it's one cable but it splits in two if you trace it). Several months before I replaced it, I noticed quite a bit of corrosion on the battery terminal. I would clean it off w water & baking powder, but it would come back. Then my car started having trouble starting. I took the batt out and cleaned the terminal, but when I took the cable bracket off of the term it disintegrated from massive corrosion. I eventually traced the corrosion several inches back on the cable while removing the protective rubber hosing. Took it to the dealer who informed me they'd have to order a new wiring harness and replace all the cables in that bundle (there are other various wires that are all "bundled" together) at a cost of well over $1000. Took it to a mechanic who separated the cables from the bundle, removed and replaced w better quality cables. On online forums I've noticed other owners who have the same problem. Looks like Mazda used substandard cable for the positive side. Also, had to replace the battery due to it constantly being drained and not recharged sufficiently. Corrosion was a distinct blue/greenish color. Mazda should address this and replace these. They don't even need to replace the entire wiring harness as the dealer stated!.