Golden Sky - Interior design contractor refusing to complete work

I have given work to a Pune based interior design firm Golden Sky in Jan **** regarding design and build of my kitchen. The work included consultancy, modular kitchen, breakfast counter, storages and electrical work. I have made full payment for consultancy and **% of the amount for rest of the work as per agreement. The work was to be commenced within ** working days and completed in a week. They did not start the work until June citing lockdown. After starting work nothing has been finished. the major issues are-
*. No regular work ever commenced
*. Modular kitchen measurements were wrong and had to be reworked. Still partially done.
*. As per agreement hettich components were to be used, they have used only few hettich components, rest are substadard
*. Many items like garbage bin, cutlery tray etc. are still missing.
*. No material ever purchased to start the breakfast counter work.

They have been delaying work citing worker unavailability, but they never purchased the materials in the first place. They claim to have done **% of the work and have no intention to finish it. However they refuse to provide bill of all the materials purchased with GST.