Non existence customer service

All I want is to change the email address linked to my supersonic account. I simply cannot get through to the call centre and there is no option to make the change on the portal. I am utterly frustrated with Supersonic. Their poor communication is utterly frustrating and is the reason I cancelled my fibre contract with them. Now I just have a data contract and am considering cancelling it given that I cannot get in touch with them to make a simple change to my email address. Supersonic has no interest in customer satisfaction and does not care that they lose customers as a result.