The builder charging 25% cancellation charges & interest for non payment of amount on time.plus GST

Hello Sir, I am from a real estate company. One of my client booked a flat and she paid an initial amount of 23,00,000/- the sale consideration is 42,09,000/- . The client defaulted in stage wise payment agreed to the builders due to some personal reasons. Now she wanted to continue buy paying that due amount pending for the flat. She has spoken to the builder for wave off interest and she is ready to pay the balance amount and purchase the flat. But today the builder has mailed her back with these details below: Further to the discussion with Landowner, kindly find the below details on the cancellation of apartment due to non-payment of payments and repeated reminders to you as per the terms of the agreement : Total Sale Consideration Rs. 42,09,000 Total Paid Rs. 23,07,521 Cancellation Charges @ 25% of sale consideration Rs. 10,52,250 GST @ 18% on Cancellation Charges Rs. 1,89,405 Interest on account of delays in releasing payments Rs. 5,32,400 GST @ 18% on Interest Rs. 95,832 Statutory Payments (Taxes) Rs. 2,17,379 Total Deductions Rs. 20,87,266 Refund Rs. 2,20,255 Kindly confirm the refund favouring details for the Rs.2,20,255/- Where as a common person 20 Lacs is a huge amount. How does she claim to the builder that she is not interested to cancel with this huge deduction or ask for full refund. speedy solution will be highly appreciated.