We bought this Microwave second hand and it has been working well for 3 weeks. When going to use it today we noticed that when you choose High, etc then start the timer, it has a D in front of the time. This is what was happening on Defrost only. It does not heat as it would on high. Also, I am unable to reset the clock. My partner set it 3 weeks ago, however we can not work out how to set it again now. I have tried turning it on and off. It does not reset