Terrible Service when i have yo pay off the account am sent from pillar to post

The service is terrible here,

I am struggling to pay the account that Wonga has sold to them and when I call this company they tell me my account is no longer with them and they don't know who has my account they send me from pillar to post even when I just want to pay the account and get over with them ,

It is a nightmare to get help with them, i mean why buy the account from Wonga if they are going to send one from pillar to post when one has to pay off the account.