I would just put it down to rubbish pads, rotors, lines and fluid.
Once you do a proper upgrade and providing all the pistons are free then all should be good.
Remember that the inner rears will always wear faster than the outer rears.
Proper bed in is essential as are warm up and cool down laps.
Road and Track Brake upgrade kits are in stock and good to go same/next day.
Just give me a shout if I can help you further.
Alex.