Where can I buy black leggings that don't sag, bobble or fade?

[ThSims]

I usually buy cheap Primark ones but for the amount I need to replace them I may aswell buy decent ones.

I've tried Tesco and Sainsbury's as part of my weekly shops over the past fortnight with no luck.

I'm happy to order online if somebody can vouch for the quality.

Many thanks

Calzedonia (online) or M&S indigo range.
On the back of threads on here I forked put for Boden (weirdly not lycra-ish, just saggy right from the go-get) and Mint Velvet (good and thick but way too short- kind of like going back to the 90s when leggings came in one length only)

Love Leggings are amazing