Terrible service!

When taking out my insurance policy, I was asked to do a vehicle inspection at PG Glass as part of the process. In January this year, I did this vehicle inspection at PG Glass Centurion. During the first week of September, I was involved in a car accident. My insurance company has conveyed to me that they never received this inspection certificate from PG Glass. PG Glass has been extremely unhelpful about this. I have been to their offices twice and made numerous phone calls regarding this to no avail. The manager has told me that it's not their problem and cannot tell me whether or not they will be able to provide the duplicate of the certificate to my insurance company. Three weeks later, I am still calling their offices and get told that they will call me back in five minutes or tomorrow. I find this totally unacceptable. I am currently without a car due to this error on the part of PG Glass yet they still refuse to help me!