Exsteamly disgusted in the service

We as a company bought a M-Benz Vito from CAW in Dec 2014, when the vehicle was bought we paid extra for the tail light and panel beating to be done. Today the 28/05/2015 we had a meeting with them with regards to the vehicle not having a service history and us sending the vehicle back in January 2015 for a service, break disc to be replace and panel beating to be done. Received the vehicle 2 weeks later being told that all had been done. Finding out today that the invoice we received from Lambats auto Electrical was done in September 2014 and not in January 2015 as they said. When I called Lambats to find out if the invoice was in fact for the Vito due to there being no information proving that on the invoice they started fighting. Clearly the way I see it is that they are both not willing to assist with the problem and are extremely unhelp full and are hiding something. When we asked for CAW for the documents to prove the work done the refused to give copies to us. I have been told by a few places that the mileage and age of vehicle don't match up and been doing research on how to get this information.