Delay in property possession by builder

I have booked a property with a Delhi based reputed builder in their township project on NH, 24 Ghaziabad in 2012. It was a ground floor in low rise ( 2 storey) house project. The builder was supposed to offer possession in 2014 and 95% of the payment was paid within 2 years of booking the property. In May, 2016 builder sent a letter for property inspection, but when I visited the site, the site incharge said the apartment in not ready for inspection & the builder should not have sent you letter for inspection. The site incharge didnt even bothered to get the site inspection form filled by me for that visit. I had taken pictures of property at that time. In 2016, I had sent a notice to builder attaching the pictures & highlighting the case. But, there was no response received from the builder. Then again, I had visited builder office in 2017 to seek possession & they said to pay holding charges, 2 years advance maintenance, electricity meter etc. charges before offering possession. I asked them to get the property inspected first & show the OC & CC certificate to which they said that they will arrange the property inspection but didn't responded. In Nov. 2017, they sent me a letter saying that I should take get the property registered and they have put holding charges effective Nov 2016 for not taking possession. I have sent them numerous emails seeking possession also replied to all emails received from them, but they never replied back on my email response. Please help me on how to deal with the builder against their illegal practice. Is it possible to seek a refund of the property from builder on grounds of late delivery? If not, what is the right way to deal with builder to get the property possession without paying any irrelevant charges? As per Builder Buyer Agreement document, builder has mentioned to pay maximum 5% of property value for late delivery which is very less in comparison to delay on delivery.I already tried to file a complaint on RERA website, but since the project was launched before RERA implementation, it was not reflecting in the RERA website.