I’m ok with SD on higher priced, one off items. Its rare I need to combine those. I do think the under £20 exception should be extended to all categories regardless of package size. The lower priced items are more likely to be combined too so that would solve a lot of the combined postage issues IMHO. 

Ebay really does need to sort out their CS. We need people with good understanding of the English language and the ability to solve issues rather than read off a script.