IMPROV GOODS review for POWR Sales Popup, Email Pop up

Wanted to create a simple mailing list sign-up pop up for my site, but this app was a mess. Not optimized well: mobile version was huge oversized box with a scroll bar. Desktop version repeatedly appeared blank. Emailed them for help/troubleshooting and received no reply. Deleted app and requested refund for the monthly fee. Developer declined. Bad app, bad customer service.