Agree that you should look at RAG. LLMs are not search engines so you need to connect the knowledge corpus to LLMs.
Try LLMWare's RAG implementation - it is easy to use, straightforward, and automates Mongo and Milvus set up so great for what you are trying to achieve. LLMWare also has free models in Hugging Face you can start to experiment with for experimenting for your use case.