Thanks for using the forums to speak out about this, I am sorry you're feeling a little cast aside at the moment. I do understand your point of view.
We do have flash sales for existing customers on at times, you just need to keep an eye out for them on your website, you can also have a look at this link - existing customer deals - which is dedicated to showing offers just for you.
But again, I am sorry you feel like our offers are not as good as the new customer deals, you can try chatting with our retentions team who will explore their deals suitable for you. Their number is 0345 454 1111 option 1, 4 then 1.