Momentum delay tactics, *********ly changed my payout

My son had an accident. The value of the car was not much so the car was written off. After several calls and delays we finally got a settlement quote that we agreed on. They took the car. For a few weeks nothing happened. After further calls and delays we finally got a letter to approve the account to deposit money into. (Once again I had to chase them as I need the money urgently) I noticed the pay-out was over R3000 less than agreed. After calling them They say the excess was incorrect, as my son was not the regular driver and they have revised the quote. This is after they have taken the car, and ownership papers and I had agreed on the original quote! I have tried to complain that it’s not ethical to just change the pay-out at the last minute. I need the money urgently to replace the car. But they refused to budge. Extremely disappointed in the service and ethics. They don't get back to you. take ages to respond to emails (if they do reply). 2 months and I have not been paid out (and don't have transport). This is not the 1st time they have delayed the process. I had lightning damage my alarm system. It took them 3 weeks to get a quote! That was a security issue they didn't take seriously. Now I have not had transport for 2 months. Beware!