Builder failed to send demand notice

I booked a residential plot on 29.11.2019 (signing of BBA) in a colony being developed by a builder. the payment terms were 10% on booking 20.11.19, 15% on or before 21.11.2019, 25% on 3.3.20, 25% on 21.5.20 and balance on offer of possession 30.9.20. the completion time of the project was stated to be September 2022. (The site still doesn't have water or electricity and roads are still under construction even today) I made the first three payments and after that the lockdown was clamped. the whole area was under curfew and when i received the demand note for may 2020 payment. In my reply I clearly stated that there was absolutely no developmental activity at the site so there is no question of demanding payment from me. I never received any reply from the builder for said communication. when everything became normal in November 2021, i again wrote to the builder to enquire about the development at the site but this time also i didn't receive any reply. then all of a sudden on 11.11.2021, i received a communication from the builder that my booking has been cancelled and he sent me the cheques for amount paid by me. then a long spell of communication followed and during our meeting on 21.3.2022 the builder agreed that they failed to communicate the demand note effectively to me and are ready to reinstate the booking for the said plot. After a week i received a fresh demand note directing me to pay the balance amount along with 12% interest. when the builder has clearly admitted that they failed to serve me the demand notice, can he ask for interest payment ?