I was searching for a course about improving pronunciation, when I found that the Perfect English Pronunciation: British English course has been added to the Udemy for Business catalog, so I took it and recently completed it.
It is exactly what I wanted: around four hours of examples, with minimal pairs or trios of similar sounding words that you should learn how to speak differently and correctly. For once, I'll show a screenshot of one pair so you can judge by yourself:
The pairs/trios are also grouped by two big categories, vowel sounds and consonant sounds. You get plenty of examples, precise instructions on how to vocalize the sounds (including mouth close-ups), and a few repetitions of each.