your bike has Cable Operated Disc Brakes... there are any number of brake replacements that will work...
i think you should be wondering WHY your incredibly simple cable operated disc brakes "aren't working", then repair the issue as needed.

https://www.ducatiurbanemobility.com...obility/mg-20/
common cause of Disc brake failures...
getting LUBE on the rotors.
bent cables that cause sticking or hard operation.
extensive rust on cheap cables.
a bad section of cable housing.
a cable slipped in it's cable clamp at the caliper.
pad fell out while repairing a flat tire, or during transport.

and it should be mentioned that MOST e-bike brake levers incorporate a Switch that tells the e-motor to quit adding power when the levers are squeezed, which means any replacement calipers would need to match the Pull Ratio of the Stock Levers....