Jura E8 wants to descale daily

Good morning, our E8 is doing interesting things again, maybe someone here knows what to do.
The E8 is 5-6 years old, we rarely brew more than 10 cups a day and the water is quite hard. Descaling is done with a red descaling liquid from another supplier.
The machine usually wants to be descaled after 3-4 weeks. A month ago, I had the same problem: after descaling in the evening, the E8 wanted to be descaled again the next morning.
I used the trick of simply running the descaling program again with normal water. After that, everything was OK.
The same thing happened again, but now I want to descale the machine again directly after two descaling processes (one real and one with normal water). The problem is that the milk system can no longer be cleaned automatically.
Is there a trick or is this a case for the Setvice?
Many thanks ????