Change my phone number

I changed my phone number recently and forgot to update my UC online account before I lost access to my old number. I contacted them 6 weeks ago and they said they would ask the job centre to contact me to arrange an appointment. I asked if it could be a phone call because it is difficult for me to get to the job centre. I can’t access my journal until this is changed.
I have still not had any contact from the job centre. I’ve contact the UC helpline twice since and they have left another message for the job centre. They don’t understand why they aren’t contacting me as the JC are apparently replying saying they have received the message. What else can I do? It makes me incredibly anxious that I can’t access my online journal but I don’t know what else I can do.