Agile Question

I need some clarification. What qualifies as agile? The cycle being used is a monthly deployment that goes

Development -> QA -> UAT -> Production

The issue is the business unit is using our QA environment to show users what is currently being developed. They then take that immediate feedback and state that until their new feedback is implemented they won’t give UAT sign off under the guise of ‘Agile’ methodology. This is causing backlog in the development cycle as they are continually requesting new alterations to requirements that have already been fully agreed upon. Is this right or wrong?