disgusting customer service and query response T.A.T

i purchased 2 items online from homechoice.on receipt i realised that the items were not what I wanted and followed the return process. after logging the return i waited for 3weeks and when i called in to check the status of the return they said the system showed the item was picked up.to rectify their mistake they picked the item up within 72hrs. i was told that my account will be credit however today i get a message for an installment due.and my account is R200 more than the items purchased disgusting