asking advance in between the month

Location/place: noida

Name of company/service: hp-pg

i rented a pg in nodia sec 51 with refrence from hp for my summer training…
the people are now asking for advance ac payment in the middle of the month for the rest of the period n asking money too for the previous period without any calculation.. the ac bill at the begining was supposed to be paid at the ending of the month
please help me.. and the advance they are asking is too much