Except as otherwise provided in NRS 487.6879, if it is determined that additional charges are required to perform the repair authorized, and those additional charges exceed, by 20 percent or $100, whichever is less, the amount set forth in the estimate or statement required to be furnished pursuant to the provisions of NRS 487.6875, the body shop or garage operator shall notify the owner and insurer of the motor vehicle of the amount of those additional charges.