I have been a part of testing team in T-systems. The environment and work culture is worst. Politics is the major aspect there. Even work was not good. Only test case execution was performed.
Now it may be a better company as Cognizant has taken it over. There are some mangers there who only believe in politics and favoritism. Worst experience in my career was with T-Systems.
Please prefer Cognizant for work but never work in T-Systems