Excess bill paid not being refunded - tenanat

As a tenant I was paying the electricity bill as per the bill I was getting. When I came to know that I was being charged in excess I contacted my landlord. He said he cannot help and that I should contact the electricity company. When I contacted the electricity company they adjusted the excess amount and now the electricity bill is in negative. As my agreement got expired I decided to leave the house however the landlord is now not willing to pay the amount that is in negative. He still stands to benefit from the negative balance as he would let out the premises again, he can get the refund by cheque also. But he is not willing to do any of that and is asking me to get a refund from electricity company.