Phone Repair of LG G4 Bought at JB Hi Fi

Any advice would be appreciated here.

I bought an LG G4 from JB Hi Fi in November 2015 on a Telstra plan. Long story short Telstra had stuffed me around and I managed to negotiate a good discount on the 24 month plan.

In late January the phone developed a fault where the WIFI and Bluetooth wouldn't switch on. Power on and off, factory reset, battery removal, workarounds not requiring rooting in the following link all tried without any change.
https://www.youtube.com/watch?v=4W8YJMDFM88
http://forums.androidcentral.com/lg-g4/563765-lg-g4-wifi-sig…

JB Hi Fi replaced the phone telling me they had a 90 day replacement warranty. They didn't have one at their local store so I had to go to another store to pick it up, but I was pleased to get a working phone the same day. The only headache was setting the thing back up and expense of driving around but that's the best you can hope for. Basically no complaints.

So yesterday morning this second handset develops the exact same flaw. I came in to work early today so I could take time off during business hours to drop it off at JB Hi Fi, which is what I've done. I didn't bother with a loan phone because the best phone they offered was a Samsung Galaxy S4 which is my last phone and which I still have.

I must admit I signed the paperwork without reading it thoroughly as I was in a rush. I also made one other mistake and that was not to take pictures. Although that'd only protect me if it gets an external scratch. The thing has a screen protector on it and I have multiple back cases. But it really is quite immaculate. I treat my phones well. Still…

Here's what I'm finding distressing. According to the repair tracking website they've sent it to this place - Roadhound at Cardiff.
https://www.google.com.au/search?q=CARDIFF%20electronics&tbs…

Most of those reviews are not very encouraging to say the least. They said it was being sent this afternoon and I'm not sure if I have any say in where they send it for repair.

Looking at a teardown of the phone I'd say the motherboard will be replaced. If so I just want it done properly.
https://www.ifixit.com/Teardown/LG+G4+Teardown/42705

I'm not very hopefully of this being repaired well. But is there anything I can/should do at this stage?