DIY Doctor UK DIY Forums

Good afternoon all, I'm looking for help or guidance with regard to my 5yr old Ferroli optimal he plus 38c.... for weeks now it has been vibrating so hard I feel like its going to come off the wall accompanied by a horrendously loud noise.... it's also boosting itself every 3 mins even when no heating or water on??? I've got a video but can't attach I've had 3 plumbers out to look at it n none have been able to repair. I'd love to have anyone's thoughts. My 2 kids are terrified every time it starts....