The T&Cs say clearly [to me] that Ming picks up return courier if under warranty.
Given what's in black and white, some in Team Ming might not have received the memo or simply forgot/misunderstood(?). Given the extra stress & pressures of the pandemicrisis, it could lead to erroneous execution and an overriding of established policies/customer service essentials.
[ In other industries I've seen this happen. For example, bankers insisting on practices in contravention of law. They only came around, begrudgingly, after I asked to call in the compliance office. ]
Incidentally, since Ming is an online brand and has zero ADs, it really should be basic that the brand absorb all freight costs during the warranty period, no?