Discovery Bank charges insane interest rates and their customer care service is pathetic

Discovery does not respond to email and even if you call their call center they will promise to respond via email, they don't!!!!!!!!!!!!!!!!!!!!!. You write emails to them using emails provided they don't respond, their customer care services is pathetic. I wrote to them asking why they had charged me 17% interest rate on my credit card when the repo rate is at an all time low but they do not respond. How else should I get of you to get an answer?????? You write to their complaints email, they don't respond again. There is no way of getting hold of them to resolve issues basically!!!!!!!!!!!!