Navata Road Transport — Asking for extra money

Address:

Navata Transport,Srinivas Center , Nandyal,Andhra Pradesh

Hello,
I regularly use navata transport for shipments. Every time i visit navata transport at nandyal branch they ask me to pay extra money on top of the bill saying that “coolie charges “. Not sure weather navata is paying them salaries or not?
I feel like giving tip to them but they should not force a customer to give extra charges.