DHL dispute - unsatisfied

DHL express/International's service is not up to standard. They quote you in person an amount and when the invoice is issued, they said a mistake was made and they double your amount. I had to explain it more that 5 times and send emails regarding this dispute. Ernest Ramodipa is not very understanding and a bit rude. The new sales excecutive, Nicole de Beer, is just as bad as all of DHL she does not even reply to the emails or messages to call you back..... this is really bad service!!! How can you get a shipment receipt for 30 volumetric weight and then on the invoice they charged you for 60 volumetric weight. As I said to the accounts department it is not my problem if a mistake was made because it they quoted me R22k then I wouldn't have send the goods to India but an amount of R11k that was quoted was accepted by us. We are a customer of DHL for more than 5 years and really this time they have pushed me to my limits. I have instructed them to close the account with immediate effect. I have paid them the R11k which we were quoted and as per the Shipment receipt. Very unsatisfied customer