Bug & request ban for player

There is bug that player abusing , i proposed him ally he take my capital and accept ally and after 2 round I lose ..I was not possible to quit ally and attack him or defend my city...
I will upload acreenahoot proofa ,I also request ban for him bcs this is not his 1 st time.

This should be removed bcs im not possible to defend myself ..its just wrong ..How someone can by my ally if he take my capital? No logic