National Highways Authority Of India [NHAI] — Not allowed to buy return toll

Hi my name is ajinkya resident of mumbai i often use the bandra worli sea link I don’t have a car so i travel by cab so every time i try to pass the toll and ask for a return toll i am been denied the return toll giving the reason its not allowed and every time i have to buy single tolls and pay extra money and the company named MEP is just looting its costumers