Terrible customer service from Luno

I need to change my mobile number on my Luno account so that I may authorise transactions. So I go through the process of changing the number and it tells me that the number will be changed in 48hrs. 48hrs comes and goes and the number is not changed. Then I email support@luno and I get a message to say they will get back to me in 7 business days. Seriously, I though customer service was improving in the world but this new technology company appears to be going backwards. How am I supposed to do any transactions from my account like this? Luno didn't wait 7 business days to take any fees from my account. There is no telephone number for me to contact either