breaking of consumer rule 8 of CPA

23/12/2014 my 82yr old grandmother bought my daughter a babyborn interactive horse for xmas. She didn't want me to keep the slip & unfortunately lost it. At the begining of Feb the toy stopped working. 25/02/2015 after major fights and lack of service delivery from Toys R Us (TRU) cresta i contacted prima toys directly. 23/03/2015 when Andre contacted me i asked for a for a full refund & he said it was prob just a faulty toy he'll get TRU cresta to swop it out. The Sat when i went to TRU cresta they didn't have stock so they arranged with TRU lonehill to swop it out fo me. I requested a new slip but they told me it isnt necessary as they have it on record that ive swopped it out now for future i must just keep the box with the price on. Last weekend the horse packed up again. I contacted prima toys again & they arranged with TRU fourways to give me a \FULL"refund. When i went to return the item i was only given a R399 refund instead of a R699 refund despite the price we paid being on the box. I was informed they will only refund to current retail value. Nw they IGNORING my emails & wont give me my box back as proof. Surely this is ******* & against consumer right no 8 of CPA. """