Poor service

I had an account at stern jewelry which i paid up in 2019july 13. Iwas so puzzled last year when i wanted to buy a new home that i am owing stern i went to stern brach i was told that my account has been ganded over i called their customers service their couldn't give details of their collectors thier asked for aprof of payment but i lost it i still have prof of EFT i have send them that sms but thier still cant. Lear my name nor give me their debt collectors details what kind of services is this are their really that incompetent. Am falling to buy my kids a home cause of the money I paid am willing to pay ot but their cant let me cause their cant give their collecters details