Upcoming lease renewal in Alabama

Sir, Southern Towers, LLC constructed a cell tower on our property in 2010 with 5 year contract renewal increments. We presently receive $700 monthly with 10% increase every 5 years. AT&T is on the tower and apparently they have increased their fees to the tower lease company because we have been offered a "buy-out" offer that has increased considerably over their last offer. We are not interested in their buy-out options. In about a year the first contract renewal will take place and we would like to know we are getting the most benefit from the next 5 year contract. Can you tell us what you'd require to handle negotiations for us or assist in the negotiations? What fees could we expect from you and what benefits might we expect? Thanks and will look forward to your reply.