Poor customer service and struggle to close card

I have had a horrible experience with RCS and my Game store card. I requested to change my debit order details 4 months ago and have not received any feedback from them since then. I then decided to settle my account to avoid being arrears as I was unable to change my debit order details. I managed to get through to the call centre easily when requesting a settlement balance and was told I would have to call back again after the payment if I wanted to close my card. I have not been able to get hold of them ever since. They have high call volumes or make you wait for 30 minutes or longer for a consultant. This is unacceptable. It is my right to cancel the RCS card if I no longer need it. You cannot make it inconvenient for me to pay for the card then force me to keep a card I have gone out of my way to settle, by ignoring your customers. Please sort this issue out promptly!!