Ibibo Group / Goibibo — Regarding change in schedule of my flight and no response on raising request.

I had booked a flight for Chicago from Delhi for 8th of August, that had the itinerary from Delhi to London to New York to Chicago. Later, the initial flight from Delhi to London was rescheduled to 9th August, while keeping the connecting flight the same, i.e. 8th August. Naturally, it was impossible for me to board that flight. So, I tried to connect to the numbers for customer helpline for Goibibo and the airline, i.e. Delta Airlines. Upon getting no proper response, I sent an e-mail on Goibibo's customer support email ID, which is also not being responded promptly, given the amount of time left to board the journey. Also, there is no avenue to connect to the booking agency through a contact number, which worsens the situation since I am not given any information about the resolution of the complaint. The customer service is deplorable. I am attaching herewith the screenshot of e-mail communications with the booking agency. I need a proper rescheduling of the journey 1-2 days later so that I can reach my destination as planned.