Added costs to my invoice without approval

Endless issues with Shilton shadrach and staff from parklands branch in Cape Town. My car was diagnosed on 5 November 2018 and promised back to me on the 7 November 2018 I have already paid half of the deposit which I was forced to pay for them to start the job... It is now 14 January 2019 and Shilton sends me an un unacknowledged with no approval for my invoice change bill of R66 000 when he knows full well that my bill is only what we agreed upon on my original quotation of R15 000 which I have already been forced to pay half to have my vehicle returned in full running condition as per booking of the vehicle and agreed quotation that was given to me the first time .... I can not have Kia passing the buck for incompetence and ********* behavior, also on my quotation there has still not been any mileage reading taken or time promised(7 November 2018) which was left blank after numerous requests to have it filled out with the correct information that was given to me on the day of my vehicle booking... please could some one help me resolve this issue because it's been almost 3months and Kia table view can not assist me... ********** 343