Consumer Redressal

I had booked a flat with sobha developers Bangalore and have paid around 35% of the total project value. This is a underconstruction flat and they send me ambiguous ledger statements. They have applied 24% interest on unpaid amount and this is recurring interest where-in an interest of 4,000 INR has accrued to 16,000 INR in just 5 months time. As I know that its my fault on not paying on time, now that I am asking them for a proper computation of the interest and let me know the final amount I should pay off but have not received any mail from them since then but only daily payment follow-ups and rude remarks from the sales agent of Sobha Developers, Bangalore.