99 gmc sierra

So my husband has a 99 gmc Sierra that he has
had for about 1 year now. When we bought the
truck it already had hids installed as head lights
and of course we have had nothing but
electrical/light issues since we have had it. There
are so many issues that I don't know where to start
so here I go.The headlights and taillights both
come on along with the dash lights etc. This is
where it gets tricky. So my husband's headlights
automatically come on when it begins to get dark
outside and the issue with that is, that I can not
turn the lights off by the switch or even the dome
over ride button. Doesn't matter how many times I
push the button in a row, it still doesn't make them
cut off. Well I noticed that the emergency flasher
button on top of the steering wheel area doesn't
work either. You can't even push the button
in/down. It's as if the button is stuck. Another
inside issue is the over head light towards the back
(more so the middle) of the truck. That light
doesn't work and for some reason the actual
plastic is metaled (of course to me that is a red
flag that there is definitely some kind of electrical
issue).  Well when you are driving the truck and you
turn your blinker on it works fine until you go to
press on the breaks. When you press the breaks
while the blinker is on the blinker stops blinking
and kind of freezes showing me on
the dash that both are my blinkers are on but not
blinking. It doesn't make the blinker sound either.
At the same time both of the blinker lights outside
of the vehicle freeze up as well. This is so
frustrating bc we like the truck but I'm afraid to
even ride in it bc I'm afraid that we might get in a
wreck bc the person behind me can't tell if I'm
turning or breaking, etc. Can anyone please give
me some advice or point me in the right direction
on who I could possibly get to look at his truck??
Any help would be greatly appreciated!