Gems refuses to give me my money owing

Goodday i am utterly disgusted by the service i was given by gems, i have a refund owing to me , so i changed my banking details last November which i had to send documents about 11 times before they actually received it , then they change my banking details but put the incorrect bank, everytime i call Gems they say that they are going to refer it to the team leader however nothing has been done my latest reference num is Mh ********** 9, i am now going to call the department of education to tell them how gems is ripping us off. I am very angry about the service i have received.