What is the monetary value of your case? Whether you need to engage a lawyer will depend on that. I do not think there will be the kind of people you want sitting on the footpath in front of the court. There may be people who will make xerox copies of documents. As far as the Consumer Forum office is concerned they will ask you to do even those things which they are expected to do. For instance the Forum has to send copies of your complaint to the Opposite Party along with a notice of the Forum. The Forum office will give you the covering notice and an envelope marked 'On India Government Service'. But you will have to do the services on your own at your cost. You have to attach copy of your complaint and exhibits to the notice put them inside the cover, write the address on the cover and send by Registered AD to the Party. If you have more than one Opposite Party you will have to send to each one of them.
Coming back to the cost of your case, in Mumbai even a doubtful lawyer will ask you to pay upfront Rs.20000/- to look at your case. By the adjective 'doubtful' I mean a lawyer who would not be good enough to win you even a simple case. Finally if the court orders costs in your favour you will get hardly a fraction of that Rs.20000/-. At Chennai the costs may be less. You can follow the advice of Dr. G. Balakrishnan. You are a Tamilian. You may know what is 'koolikku maaratikkarathu'. A lawyer will do that.
I have fought several cases of my own without engaging a lawyer. The Opposite Party had engaged lawyers. But I always won the case. These days you can get any law or any judgment cited by the Opposite Party on the internet.