Faulty ont box not being replaced

My service provider is Afrihost and for the past 4 months, they have been trying to get my ont box replaced but you keep closing the tickets and have you made no attempts at contacting me to send out a technician. How difficult can this be. I'm paying for a 1000Mbps line and not even getting speeds of 250Mbps. I have done everything that was asked including changing lan cables and routers. The tests directly from the ont box is less than 250Mbps. Someone needs to take responsibility and resolve this or give me details in where I can get an ont box and I will sort it out on my own. Cause clearly I'm paying you guys for nothing.