The problem I ssuspect is that while giving advice costs nothing, if they give incorrect information then it could cost them a lot in litigation costs. My TA not only wont give advice but also makes me sign a form to say that I know it's my responsibility to make sure that I have ay appropriate Visas. I'd be surprised if any TA would be willing to provide such info free of charge without signing some sort of indemnity to the effect that if they get it wrong othey are not liable ofr any losses or inconvenience you suffer. this would make the advice worthless.
When we went with Celebrity to Australia and New Zealand they advised we needed to obtain a visa to enter Australia and had a company who did it all within a few days of us emailing in the details and sending a copy of our picture page, via a special delivery option and I think the total cost for two was around £36.