> Previuos SW version was the same but with different colours.

This means it is NOT a software change! The dealer is talking rubbish.

If the colours on the rear-view camera are wrong then the reason is clear.

Two colours on the monitor have been swapped - ie: when they repaired the wiring, they mixed up two of the three colours.
The monitor is driven with Red, Green and Blue (RGB).

To determine which colours are wrong, print a piece of paper with three squares on it: pure red, pure green and pure blue. By pure I mean when you use the computer to generate the colours, use RGB values of 255,0,0 for red, 0,255,0 for Green and 0,0,255 for blue.
Label the coloured squares (in black) so you don't get confused.

Hold the page behind the car so it appears on the rear-view camera, and compare the pic on screen with reality.

My guess is that blue and red are swapped, as your green satellite symbol is still showing correctly in green.

Then either go to the repair shop and demand they fix their mistake, or fix it yourself.

The monitor has a blue connector on the rear, with numbered pins 1...18.

The relevant pins are:

1 = Red
2 = shield for red
3 = Green
4 = shield for green
5 = Blue
6 = shield for blue

You'll see 3 x coax cables going to these pins (or a number of unshielded wires, depending on how the repair was done.)

If red and blue are swapped, then remove and swap pins 1 & 5 (signal) and their shields, pins 2 & 6

That will fix the problem.

> I have read about coding of a replacement nav computer, what does the "VIN 7er" on the service menu/telematics settings mean?

The nav should be coded to your car so it contains the correct vehicle information.
When the nav leaves the factory, it has default coding, where vehicle type is 7-series (7er) and VIN number is empty.
If the repair shop did their job correctly, they would have coded the nav to your car, and you should see your VIN number (last 7 digits of your VIN, in format AA12345) in the nav.
If this info does not appear, then the coding has not been changed, and the nav is in default factory coding.

This means that some items may not work correctly for your car.
eg: BMW Assist, Auto-Emergency Call, both require coding to work properly.
(default is no Assist, no Auto Emergency Call, and no SMS numbers or Customer Service Number programmed)

Also, the radio type, if not coded in the nav, may not be correct for your car (default is BM54).

And default languages (with no coding) are GB, DE and FR.
During the coding process, the dealer should ask you what languages you would like, or otherwise he will program with the default 3 x languages for your region.

If your nav was not coded, you should complain to the dealer.