They seem fairly new with no reviews, but the price was very appealing so I decided to give them a go. Very good and pleasant experience and communication. Showed up on time, did the testing and even cleaned up. Michael did his job properly and professionally.
My previous experience was a regular from [x company] who got too complacent, attached his tools to the backflow device, took some photos, acted a bit shifty pretending to do some work and wrapped up in 5mins. $350 all up for one small device. (and that included a discount..)
If you can relate to the above, I recommend giving Sydney Backflow Prevention Services a go. I expected medicore but got a 5 star service.