You have to trust that they really

You have to trust that they really are going to come up with some great slogan ideas for you to choose from,and you can't really keep going back and expect them to go through the process indefinitely after paying for an initial session if you really don't like the slogans that they give you,or feel that they misinterpreted your brand's vision,most slogan writers will want to make it right within limits and these limits will usually be made very clear in your initial contract.