cold calling to find customers?

I help run an auto body shop and currently we are lacking customers. I feel as if finding one customer at a time is a long and tedious process. So I decided to start searching for people who need more than just 1 car worked on. I was not sure where to look at first than I looked at other business around me and which could benefit from the one I am currently in.

I ended up calling a few used car dealerships and actually found a client. That being said, it took way to long and did not feel like it was worth it.

Is there a way to grow my "cold calling" list? I want to be able to call number after number without keeping to have to find a new business after every call.

Any help is appreciated thank you!