e46 audio upgrade question) 318ci 2001

[lumberjack]

Hi all

some years ago I took my car to a bmw agent and asked them to fit a sony T70MX 6cd player as it played mp3.

After a while it was causing the battery to go flat so took it out, I now want the facility to connect pendrive, bluetooth etc.

Trouble is they rang when fitting and said it would not fit in the usual place (above satnav system) and would need to be screwed into the roof of the boot, which I accepted,
It never clicked that they retained my existing system and left a blank space where I suppose they tried to fit the new stuff.

Considering the above, what can I buy to fit my needs, the car has only done 70k and I wish to keep it having had from new so would appreciate advice about what I need and what is possible (or not)

thanks

ps
I have an android phone not an iphone or ipod