change value

Hi Friends,

I am stuck at problem, and was hoping if anybody could please help me out with a VBA code that will run with Column G.
I have an excel sheet, in cell G2 I have Team A or Team B or Team C.
Cell position G2 is deciding factor.If G2 is Team A then anything below it should be Team B, or if Team B then anything below it should be Team A.
In this example file G2 value is Team A, but G3 is team B then automatically the corresponding value of C changes to "Retest on next sample".
Then G4 is team B then automatically the corresponding value of C changes to "Retest on next sample".
Then G7 is team C then automatically the corresponding value of C changes to "Retest on next sample".

But if the cell is blank (that means no team) then the code will not change the cell value in Column C.

I am attaching the example file for reference.
Please help me friends,
Thanks in advance,
best regards,
me