Mighty Jaxx US review for Shopify Marketplace Connect

We installed this app to connect Amazon and Walmart marketplaces to our Shopify store. Unfortunately, we were unable to link our products. We opened a support case on the 15th of July, and despite assurances that Marketplace Connect's developers were working to fix our issue, almost a month later and we still have not had a response. Shopify Marketplace Connect is holding back our business due to poor support, forcing us to look for alternatives.