The secret to getting builders to respond post-booking

Since January I've been shortlisting flats in Faridabad, thinking of upgrading from my 2BHK in Sector 15. I'm eyeing Goyal Luxury Floors by Rahul Mangla in Neharpar, prices around ₹90L for a 3BHK look decent. But the biggest concern for me is post-booking customer support. My current builder, once money was paid, ghosted me. I heard a hack: always cc their RERA compliance officer or legal team on emails for faster responses. Has anyone actually tried this with Goyal Luxury Floors or any other builder in Faridabad? Does it work? Also, what was your possession experience like? Any nasty surprises with hidden charges or construction quality issues popping up right at handover? The whole OC and maintenance handover process worries me. This is a big investment, especially with DM Expressway pushing values. Just want to avoid post-booking headaches.