What can I legally say about a company's bad business practices in my local paper under opinions without getting in trouble

The auto repair shop became hostile when I had questions about the charges and told me to take my car and get off the property without the car being fixed all the way. They agreed to let me pick it up the next day after the work was done. I paid the bill in full and asked for the original parts back. I was told they were not giving them back to keep as evidence in case I called the BBB. I never disputed if the original parts needed replaced, just ans explanation of why thy were so much higher and to have the original parts back. I feel they are using inadequate business practices and deceiving the consumer.