ESP and ABS share an ECU. It's mounted on the hydroblock in the engine bay (passenger side bulkhead area). Sensors are wheel speed, steering angle, yaw sensor, brake pedal switch etc. ESP ECU is linked to the engine ECU to decrease throttle opening angle and vary spark advance.
No, that's the UCH. UCH is a gateway and ECU for various electric systems (window motors, wiper etc.). Then you have ECUs for the engine management, ABS or ABS and ESP, Airbag etc.
Could also be a fault in the TC/ESP system!? Proper diagnostic machine needed.