Leaking air Hammerli Pnuema Elite 10

Sent this gun in "twice" to Umarex, first time they said they replaced a valve, I got it back and filed it with air, two days later all the air was gone. Second time I sent it in they said they could find nothing wrong with it and they filled it with air, shot it, and kept it a day or so and returned it to me stating nothing wrong with the gun. I filled it with air 188-195 Bar and 24 hours later half the air was gone and by day two it was empty. Frustrated with this issue, anyone have a idea what could be the problem? I've had the gun 6 years with no other issues.