Extremely slow service

I am still waiting for my fibre installation to be done at my home from last week Thursday where someone from openserve contacted me and said that I will be contacted the following day to schedule the installation. It is now the following week Wednesday and still no contact has been made. I started phoning my service provider after I held on for more than half an hour to speak to a consultant from openserve.

Who can I contact to set this straight without holding on for more than half an hour with no reply.

*** is my contact number