Delayed payments for works done

We ( a company registered under MSME) had done industrial civil works for an industrial unit in Vizag on Cost plus model. However, even after giving proposal for converting into a Work order, they have not processed the WO. When we put up our first invoice for works done, they have only paid 37% without any justification. Because of such issues like delayed payments and delay in issuing the WO, we decided to quit the works and provided our final invoice in Oct 22 for reconciliation. However, they are now refusing to make full payments. We also done some design works for their other units in Kochi and Singrauli, which they are refusing to pay on premise of Value Engineering. Wanted to know what remedies are available to us and if MSME Samadhan is applicable to us in absence of any formal WO issued to us.