www.brandlock.io review: They still haven't paid me the full sum

I worked for the company www.brandlock.io. We signed the contract and they promised to pay one rate, but when I finished the job, they paid me only half of the sum. After that I tried to get money from them, but the situation hasn’t been changed. No idea what measures to take now. Maybe someone has any ideas how to return money back, please contact me then or leave a comment. Thanks.