Service Fraud

I hired an interior designer for my interior work, no legal documents were agreed. However Interior designer promised high quality of work, tools/stuffs from Godrej or any better company and strongly suggested that bubble sheet to be used to avoid any seepage in future. They promised to deliver it on 15th Feb, even I arranged Grih Pravesh pooja in second week of March, gave notice to my landlord to vacate his flat in March itself. However, work not completed so far. Faced seepage issue and when checked further it was noticed that they haven't used bubble sheet in kitchen and I doubt anywhere. I have paid 75% of amount, work done so far is round 80%, stuffs used from local companies. Interior designer is pressurising for balance payment, however I dont want to pay for faulty work. Bubblesheet is must and he should use only stuffs as he promised. How can I secure myself, I would prefer to get refund and let him takeout any work he has done or anyhow place bubble sheet