Very bad customer service

I have been a Cellc client from 2009, i have never been in arears on my account. Today 01/03/2020 iwent to Cellc Vaal mall to process my upgarde, and i choose the Huawei T5 Nova, however they refused to process my upgrade because i don't (according to them) qualify for that specific phone. How can i be a client for more than 11 years, and can't get the phone i want? I know what i can afford, and what not. I am a very disappointed customer, and will be closing all my contacts with Cellc. I got treated very badly. Cell c should rather close all their doors, they are pathetic to say the least.