AJuar Mine worked 5 or 6 years and has never had that problem, I use RO water with Bicarbonate.
I have heard of one machine that never had an O ring fitted in the valve, that was easily solved.
The one way valve problem is common in many machines (not just vesuvius), especially rotary/gear pump ones as vibration pump machines also have the vibration pump acting as a second valve. The problem is almost always caused by poor water quality, but sometimes particles of something in the valve (e.g. if filter cartridges are used, I never use them).
The Vesuvius uses a commercial water distributor, so it’s not a quality problem. If fixed, the machines should last many years, 6, 10, longer without a problem, as long as good water is always used.
P.S. The problem may have been cause by the times you used mineral water, especially if water has other things in it that can gum up or desposit on the valve.