Does anyone one know how to go about dealing with IRS when they wont give any information as to what is needed or even missing in my already filed tax return?

I filed in February of 2025. received a letter in March and have continued to receive letters asking for extension of time. The letter does not state the issue or what is missing and when I call the IRS agents Arnt helpful. Now they are saying wait till February of 2026 to call again