Overcharged & deposit withheld

We rented a car during our holiday in Cape Town, from 2 April to 8 April. We used [URL Removed] & our Vitality membership to get a discount. Our Kulula booking ref was 4FE5Q7K. After returning to Joburg, we received our invoice. Our Europcar Res No is ***. When I checked this invoice against our Vitality booking, I noticed we had been overcharged. I sent an email to Europcar last Monday, received and auto-reply but nothing else since then. <br> I filled out a feedback request from Europcar and have had no response to that either. We also called Europcar on Saturday and had Serati send an email to Europcar Customer Care and still nothing.<br> And to top things off, it has been 12 days since we returned the car and the almost R8000 they reserved for deposit has still not been released back to me. I was advised when hiring the vehicle that the deposit reserved would be released back in to my account within 3 working days after the return of the vehicle.<br> I want these problems sorted out but no one seems to care or do anything at Europcar..<br> Please can some one give me some answers?