The work was to be completed in 45 to 60 days which is delayed by one month now. The service provider cannot relied. Seek refund of advance paid approach other reliable interior decorator. Issue a lawyer's notice seeking refund with interest. After that file a complaint in District Consumer Commission under Consumer Protection Act, 2019 under which proceedings are very fast. You will ger refund with interest, compensation for mental harassment, cost of complaint and lawyer's fee.