I like this part, "Image if for general illustration purposes only, and may not picture the exact parts of this listing." No shit, that's a picture of Renault Clio REAR rotors and pads!
You've missed the point, what you paid for them is irrelevant. Both Bendix and those RDB pads are VERY basic cheap trade servicing pads, designed to make workshops as much money as possible. To put it in perspective, those RDB pads we sell for $35, and still make very good % on them! Imagine what they cost to make by the time the manufacturer and importer before us make money on them...
We do both Bendix and RDA, and of the 12-14 (I loose count) brands of pads we do, they'd both be in the bottom half in terms of quality and bang for your buck.
To try and be more helpful, I'd say most of your current problem is because you've put the RDB pads straight on the pad material on the rotor left over from the Bendix. You didn't machine or replace the rotor when you changed pads did you? (Didn't read it anywhere, but you may have just not mentioned it).
Feel free to give us a bell on 1300 884 836 if you'd like to discuss it over the phone (probably easier).
Regards,
Greg