Failure to respond to cancellation of credit card

I have been attempting to cancel my discovery credit since the beginning of October 2017 and I have received no response. There is no possible way to navigate the website in order to get an international dialing number in order to contact anybody who can assist. I have provided the cancellation forms, my contact number as well as a Power of Attorney for personnel that can call and yet nothing has been resolved or remotely taken off. This service is extremely disturbing. What is even more disturbing is that discovery took a double payment from my account in order to settle the apple watch I purchased through the Vitality program and took 2 weeks to refund the money. This was THEIR administration error and "unfortunately" I had to pay the price. Quite shocking service really.