Builder extra charges

Is it normal in karachi that builders of apartment will charge huge amount on account of extra charges for lease utilities charges at the time of possession. In my case the builder already take 600k for utilities charges and now again send us one another 600k for utilities,leaae charges etc as full and final charges.
The builder also refuses to provide breakup of these charges. Some of other appartment owners are going to complaint to abad and than to ombudsman. Any one have any experience or can suggest any thing
Thanks