Creating a Turnkey Selling Landing Page

Good day. We promote triathlon coaching services (a very narrow niche).
There are 2 landings: Texto oculto, both work terribly, conversions are no (advertising is set up well, visitors are targeted).
It is necessary: to analyze errors, delve deeply into the topic and CA and make a turnkey good selling landing. Any questions, information, etc. - I'll give it all.
Just creating a landing page is not interesting. You need to understand the target audience and a well-thought-out sales structure. Please indicate that you read this in the application.
Write an approximate price and timeframe.