Interior designer not doing work

Hi, I'm from Kolkata, and have contacted an interior designer for my home. I have paid him approx 35lac for all the work that he quoated, but the quality of work is not satisfactory. For instance, 1. the marble polish was not done according to the quotation, 2. only single coat painting is done, but in quotation it's mentioned 3 coat. 3. Air is forming inside the sun-mica, and many more. And now he is asking for more money. I said I'll pay the same, but only after the fixes are done that was intimated earlier. But he is saying, he'll not continue his work, unless the remaining balance is paid. And from last 4 days he stop the work. What should I do? FYI, all the conversation with him is done on whatsapp.