No action on insurance claim

I submitted an insurance claim on the 16 March to MTN for a cracked screen. Got their standard email response saying they had a problem and would respond in 5 working days. 13 days later and no response to my follow up emails except the standard acknowledgement of email. Tried the call centre - after eventually getting through 5 working days ago and a promise that it would be escalated still no response. Called again on Monday - empty promises of escalation. No action. I am now desperate as this is a business phone and I need it fixed. It is really unacceptable - a promise of a turnaround of 5 days is fair but no action or information in 13 working days is crazy. Just don't know what to do next as call centre not taking any action.