Bad customer service

I joined debt review almost a year ago, but they refused the negotiations so we decided to remove it, now I believe my account was handed over to collections but I never received an information which the collectors are, so how am I supposed to make arrangements as I’m almost done paying my debt review, they will be random call and I would ask to send me an email to this date I have not received anything. I just want to pay my account and close it as it’s been a nightmare and regret using this bank as the service is the worst. Now I need to start paying of the account who do I pay? To which bank account? As I need this account closed as soon as possible