Peter, the internet shows several solutions you could use. This is one:
https://www.triax.com/products/terre...lp-filter-ch48
Even good old Bunnings has a solution:
https://www.bunnings.com.au/antsig-4...ilter_p4360444
For $21.42 It seems worth a try.
You can send a bill to Vodaphone, but good luck with that.