Alternator/battery charge light!

Hi, have a disco 3, which has had many of the normal issues that discos have air suspension pumps, EPB adjustment. Now I have a problem that even the local independent LR garage are stumped by. Started with the battery charge light coming on and staying on, then it progressed to a pulsing of the electrical systems. Fitted new alternator, back to just the battery light on the the pulsing was back. Checked the the battery charge with a volt meter and alternator over charging at about 16 volts intermittently. Garage checked it out and said the issue was alternator so got a second one fitted it but still the same issue. Most of the warning light flashing on and off on the dashboard and the parking brake was being applied when driving along. Local independent LR garage suggested fit a Denso alternator and issues likely to go away. Have done this and fitted new battery. No pulsing any more but battery charge light on even though it is reading 13.8v on the meter. The EPB still seems to be applied while driving . Any ideas or help would be appreciated. Ta