There is no system of calculating the fee/charge of a lawyer for his/her service. It depends upon the nature of case/service, time spent by the lawyer/priority of case/ paying capacity of the client/area to which the lawyer/client belongs to and many more. But it should be logical and shouln't hurt the client aswell.
Un fortunitely Lawyers in India cheats too much. They avoide to issue bill for their services. Always demand money saying they wants to bribe court staff.Un necessary postpone hearing dates. They do not have any staff. Un prepared for the case. This is my experience