Woah! That’s a terrible experience, you should definitely get a refund!
Some online resources which may help you:
Coursera has a very good Introductory course on UI and UX design, with topics ranging from prototyping, wireframing & user studies. Attended the course a couple years ago, and it’s been incredibly useful!
Butterick’s practical typography website is a great resource for Typography studies
Nielsen Norman Group’s articles often have great insights on interface design:
If you’re designing for a specific platform, you could read their human interface guidelines, which provide a lot of practical help.
(Make sure to watch their WWDC sessions, which often talk about basic principles in UI Designs)
If you haven’t already, check out the Design of everyday things by Don Norman. It’s definitely worth reading to get a hang of basic design principles.