Thanks for bringing this up.
I had made an RTI application regarding the street lights in Mumbai, and I only got replies to a) How many there are and b) what is the 'total' electricity charges for the same. Other details like the time and per unit consumption were not given, saying that this information is only available with the Electric Companies, ie, M/s BEST u/t, M/s. Reliance Energy, and M/s MSEDC.
Can I make an application to these companies directly? Where can I raise my second appeal if they refuse to give out the information?
If the original PIO (where you made your initial application) did not have the part of the information you asked (because he seems to have answered a part only), he should have rightfully transferred a part of your application to the PA which had the information (in this case the electric companies). Since he has not done that, he is at fault.
You can appeal against this if the time limit for first appeal is still in your favour. The first appeal has to be made to a officer who is higher in rank to the PIO. Normally most PA's have appointed Appelate Authorities under RTI Act. Your PIO should be able to tell you (he should have mentioned the appelate authority details in the reply that he gave you). If difficult, just address the first appeal to "Officer for First Appeal under RTI Act 2005" etc...
If time limit for first appeal (30 days from date of receipt of information) is over then, you will have to make a new RTI application (just like the first one) to the Electric Companies asking for information that was not given to you earlier.