What do I do after we found a rusty thumbtack at the bottom of our hash browns?

My husband and I were getting breakfast this morning. After dumping out his hash browns onto a plate and eating 5-6 of them, he noticed something under one. Upon further inspection. we found the something to be a rusty thumbtack or nail. We called the food chain we purchased the food from 5 different times with no answer, so we went up there. After asking to speak to the manager, explaining what happened and telling her we want an incident report, she told us she doesn't have a report to fill out, and she'll just let her manager know. When we asked for the managers phone number, she said it was on the receipt. We tried to call only to find out that the number on the receipt is the same number we had been calling with no answer. After leaving there completely unsatisfied with how things were handled, we called out local urgent care and were told he should probably get a tetanus shot to be safe.