Need advice on not continuing work with interior

I approached a interior designer in mid jan 2022 .he has a modular furniture making factory , and after asking my budget he agreed with everything we wanted in our house..I told him to see the apartment and measure it and then give quotation.we were very clear on what we wanted right from start so he knew our requirements. Accordingly he give us quotation which included civil work for our flat. According to quotation we were to pay 10% of total quotation cost to begin the work and they will give us design in 3D and 2D and final design will be walkthrough. On 18 jan we transferred our first instalment of 10 % ( total quotation cost was 30 lakhs) they begin with one design for 2 bedrooms ,but we didn’t like so they stop giving and asked us to provide Some reference design as we want.. we started giving them references and they started copy paste them in design…but they delayed giving design also till jan end they didn’t even complete the design for bedrooms. Feb 1st they told us design part will be carrying on but we need to book the plywood and lamination because cost is going to increase after 5 th feb ..they told us to do 65% payment. at that point I reminded that contract and agreement is not signed ,but they said design is taking time and but the time contract will be signed cost will increase…so I transferred them another 45% of money because they assured me that work will be starting soon. And that’s were all issues started. Whole feb they passed time with design which were not frequent and lot of unwanted things which needed correction… so I started pushing for civil work and electrical work…feb they didn’t respond properly ..march 1st they send some guy to start civil work..they use to come 2 times a week and sometimes work only few hour and used to leave early..I started complaining about slow pace of work because without completing civil work furniture work will not start ..I according to our first meeting they were to complete the whole job by may. Their designer was not working on our design…so we were not able to sign the contract … they were deliberately delaying the work by not providing design,not giving contract and agreement… by end of march not even half of civil work was completed….the work was only of 15 days if done sincerely….April first week we started pressuring them for proper quotation with proper measurements and civil work cost.. they gave us a quotation with 6 lakhs extra amount and the measurements of furniture were all wrongly done .we showed them and they rectify it.but now we are fed up .total. Of 15 lakhs is paid and they have not completed civil job which according to them cost 2 lakh.we are forcing them to complete civil job but after that we want to cancel this and want our money back…we have lost trust and definitely not able to shift in may...this person doesn’t seem like he is interested in giving back money…so how do I approach…we have still not signed anything…please I need advice