Misleading and Poor service

We made a reservation for a vehicle for 4 days and for my family. We also specified that we need a chidd seat as well which was an additional R518. With the 4 day rental(R2133) ,doc fee(R124) and child seat the amount was R R2775. We went to collect the car at Europcar at the Cape town Airport . When we got there ,a very friendly and helpful guy called Camron looked at our three suitcases and said that he is going to upgrade us to another vehicle free of charge. The car we received is also a group C vehicle. We returned the car on time as per our agreement and drove only 327km's although we had a 200km per day included in the rental. When we got he invoice we saw that an addition R711 was added to the rental amount of the vehicle . We immediately send them an email( *** ;***) to query this . Till date nobody came back to us ,explaining the extra amount . I was refunded R711 lees on my card.RA# ***. Will definitely not advise people to make use of this company!!