Single emonbase is consuming all server power


I already had this several times, but wasn’t able to resolve it:
I have two emontx in a remote location and also two base stations. Actually one base station is for one emontx but they are both within the range of the rfm69, so occasionally one base station receives signals from both emontx.

They are reporting their values to the same account of a self hosted emoncms instance (9.8.25 | 2017.12.08). Occasionally the server is under heavy load,
which has always the same reason: this account is playing crazy:
It tells for example last updated 42 hours, but the values are changing every several seconds and the last updated time bounces around:

The server logs are indicating a 503 error for the concerning IP:

I have no access to this emontx nor the base station.

What is happening here and how can I stopp it?