Invalid acceptance of quotation

I'm trying to sell my car - they gave me an acceptance letter to sell the car, but the reference was not valid, so Webuycars could not make the payment. I tried to contact MFC, and they couldn't transfer me to the person who issued the letter because the person was "On a call". I called the direct number they gave me, and IT DOES NOT EXIST. I phoned another lady in the same department - goes to voice mail every time. I've sent an e-mail, no reply. I now have to insure the car for another month. Nedbank urgently needs to join the 21st century and upgrade their system (7 working days to reply on a quote is a long time if the quote is only valid for 10 calendar days) - this is why Nedbank is not growing - and if a staff member gives an invalid number, thats a terrible break down in controls and lack of oversight. Very frustrated and disappointed.