Maintenance charges

Sir, I had been offered possession of a aptt by my builder Emaar India in Gurgaon in Mar 18. I made the final payments in Apr - May 18, however when i took leave to take possession from a remote location (I'm in armed forces), the builder had not prepared the house for handover(flooring not done, distemper pending etc.), As a result my possession got delayed and finally happened in Jul 18. The builder then presented a bill of common area electricity from Apr 18 - Jun 18 (in spite of fact that possession had not been completed stating that they had made the offer in Mar 18 for possession). Subsequently, in Jul 19 I received maintenance charges from Apr 19 to Jun 19 ( after one year of possession) - On contending that physical possession happened only in Jul 19 and one year cycle should start from Jul 19 and not Apr 19 - the builder once again expressed inability to help and stated that delay in possession is not attributable to them (in spite that the house flowing wasn't even completed in Jun 18) and saying that they had offered house for possession in Mar 18. I have cleared the common area electricity bill but have kept the maintenance charges pending for the period Apr 19- Jun 19. The builder refused to help when i visited the office also an through email. Request advise.