https://www.congress.gov/members/find-your-member
"Hello, my name is $name. I am asking you to either sponsor legislation or to support legislation sponsored by another memeber of Congress to increase funding for NASA's Deep Space Network to an appropriate level, which to my understanding is roughly $700M, about $500M more than current allocated. I'm sure you are aware of the enormous amount of value that we enjoy from space science [1], and therefore why it is crucial NASA has the capability to continue to operate this communications network in order to enable that ongoing science. Thank you for your time."
They will ask for your zip code and possibly contact info to follow up (you'll usually get a letter or email from your rep on the topic).
> The agency's internal watchdog said a project to upgrade the three DSN sites with more 34-meter antennas and higher-power transmitters is five years behind schedule, and the cost of the upgrades has increased to $706 million. That expense takes a long time to pay off for the DSN's budget account, which has fallen from an annual level of about $250 million in 2010 to about $200 million today.
[1] https://www.nasa.gov/sites/default/files/files/Benefits-Stem... (if you want specific value talking points)
The old rule was congress critters weighted a personal letter with highest weight over a form letter, over a call, over an email. Now, staffers are of younger age, and they are the gate keepers of what gets passed along. So that order of weighting may be different now. Then again, that's probably also highly dependent on the specific congress critter. AOC may be much more open to tweets/emails/etc vs Mitch McConnell or similar aged someone
They might have tried attaching this to Artemis, as you suggest, but gotten political pushback. They might have known that they can get Artemis approved without the DSN improvement and then hold Artemis hostage for DSN improvements. DSN money might have ended in the wrong Congress person's district. So many possible political reasons we might never know
Perhaps, but that's largely not in NASA's control; Congress appropriates money for specific purposes. NASA can't legally go grab Artemis money and shift it over to DSN.