Layup and Iphone preowned Confusion and horrible service!!!

Layup has given me horrible service, I have purchased a phone from istore preowned through layup so I could manage to pay it in installments. I paid the last payment yesterday and received a message from layup that the payments were complete and iphone preowned store would be in touch regarding the delivery. However iphone preowned store sent a message that there's still an outstanding amount of R1600 which doesn't make sense at all. Neither Layup or iphone preowned is giving me a clear answer of what's going on or when I'll receive the phone. I don't understand if I am being ****med here , I'm so upset and frustrated 😩