Webkul Software — The app doesn't work and they refuse to fix it

I bought the Multi Vendor Mobile App for WooCommerce module 6 months ago from webkul. They gave me an app full of bugs, they fixed some but new bugs always appear, and now after 6 months they are refusing to fix the problems because the support period is over. This is absurd, this company delivers modules that don't work and they still charge to fix their own errors, this company is a fraud.