Just like Liz Earle still did the shows for a few years after selling to Avon.Seems to me if you are on social media, there are likely to be other disgruntled LR customers. The more public the forum of unhappy customers, the more traction your complaints will have with LR, as it will hit the where it really hurts: in the financials!
Nikki and other founders are most likely contractually bound to appear for a certain amount of time for Q's benefit... it helps them promote the brand in a certain way, which bears no resemblance to reality. Also, someone needs to rein in Nikki talking about pieces lasting an eternity, as that could be actionable in law.
I think the best you can do is publically shame them, both for the quality they offer for the prices they charge... and their lacklustre customer service responses.
Bobbi Brown did shows on QVC US after she sold the brand to Estee Lauder. Part of the contract when they sell stay as the face of the brand for X number of years.
When Jo Malone sold her company to Estee Lauder pre-2009, she signed that she would not create another company for X amount of years. Then perhaps 5 years later she started Jo Loves.