delelet about 2000 contact groups with same starting sequence for name

Hi,

I have about 2000 contact GROUPS, which I need to delete. All groups start with _ModGrp and were created by a Deutsche Telekom app (according to the groups names) on my iphone and syncronized to all my devices. I´ve reported this app to apple a while back and the bug got fixed, however I still have all those groups.

Any and all help would be greatly appreciated.