escalade esv. electrical issues and recommendations

[gatorboy112]

i appologize if this is in the wrong area but please move this thread if it is.

i have some pretty basic questions but here is a run down of what has been done so far. i have an 08 escalade esv with factory nav and dual flip down screens, anda local shop has installed kicker 0 guage wire, audio control lc6i, bass knob, and i currently have a 4-channel digital audio 1600w rms amp(only using two channels) and 4 memphis audio 12s(250 rms). originally they ran the remote turn on wire to where the amp cut on only when my head lights were on and ever since the install the truck occasionally acts up with a few electrical issues. the nav screen has blacked out. the subs cut off and wouldnt come back on until i turned the truck off for 10 minutes. all the lights on the dash have came on while driving and the screen blacked out. and the truck has also shut off with the lights coming on the dash. when the radio is off it doesnt have any of these issues.

the truck went back today to get the install looked over and to fix the remote turn on issue so the amp cuts on when the key is on. they suggested it may be the alternator being too weak to handle everything and causing the issues or the battery may have a bad cell. the factory battery was replaced earlier this year with a sears die hard platinum deep cycle battery so it should be fine,but do you think this could be because i need a bigger alternator? if so what alternator do yall suggest ?

my next question is what would be a good setup to replace my current amp/sub combo. i cant use my third row seat because of how big the box is(it has 8 12s in it, bought the sub amp combo from a buddy for $300) but i want to know what yall would suggest i should go with for an amp that i can use the 0 guage wire, and im thinking a 2 sub combo would be fitting for what i want. price range for sub/amp i'm wanting to spend is 1000-1300.

I want to set up the electrical correctly. just any help will Be greatly appreciated.

thank you