Building a chatbot to act as a salesperson

Hi guys, I’m trying to develop a chatbot to handle a company’s customer service. I’ve tested some solutions like Chatbase and Chatthing, but they’re a bit expensive, and the parameterization doesn’t work properly (it’s not assertive, and I can’t get it to have a tendency to make the sale, induce the consumer to do so). I’m currently testing Flowise, as it’s cheaper, using a PDF with a commercial script.

What do you suggest so that I can build more appropriate responses? Train my own LLM? What should I do and how can I do it?

Any ideas are welcome. I’ve been at it for months, without much apparent progress that I feel comfortable putting into production.