Reduce DC 12V 30A motor's interference

We bought s kit of motor controller at this store .

We always want to reduce the interference because it greatly lowered the working distance.
The receiver and transmitter are used well with deceleration, deceleration, forward and reverse.
The main interference is from DC 12V 30A motor, the power is too big.

We tried to contact to their research and development colleagues and our motor's interference is too difficult to solve.

Why i can't insert an image from my computer?

We will be appreciated if anyone could give us some advice.

Many thanks.

Image Guide

That looks like a complex device inside that metal cage. Without some understanding of what's inside, it will be very difficult to recommend a solution.

I used a Quencharc 254 snubber on a DC12V 20A(peak) motor and it seemed to control the interference I was getting. Just put it across the "M" terminals in parallel with the motor.