I'm now on my 3rd Ideal Standard A3000 IS Therm thermostatic shower mixer. The first one 10 years old started squealing so I purchased an exact replacement. It worked for 2 months then started squealing so I sent it back assuming faulty and got another which is squealing from day 1. Moreso when I turn temperature control up or down. Am I just unlucky or doing something wrong? I have high pressure mains of 7 bar at the cold tap but the specs say max static pressure of 10 bar so I assume that's not it. Any ideas?