The dealer still did not settle my trade in car

We traded in a i30 a month ago on a Grand i10. The bank is still phoning us and demanding payment on the I 30. This is reflecting realy bad as reference on our name. We have been promised settlement on the abovementioned car two weeks ago when we traded another car in on a new I20. This trade in was a 2012 Lexus IS 350. I am dam sure that this car has also not been settled. This car has in the meantime been sold last week Saterday. We are also still waiting for fhe regisration plates on the I10. This has never been done since we have received same. They had to renew the temporarely permit already as it had expired. This is totally unexceptable. We can not accept any more empty promises from these people. Please help.