Poor customer service

I made an online purchase where i bought items for R180.Each item is R129.99 but there was a promotion of buy 2 save R80 .When I wanted to refund the items instore because it was too big they wanted to refund me R49.99 each.My tax invoice shows I paid R180 even my bankstatement shows the amount I purchased online.They called their customer services when i was instore they told me i must send an email with my tax invoice wich i did and they rep**** saying I must go to the store .I spoke to 5 consultants that told me they dont know why they charge me R180 for the 2 items but it shows on ttheir side the items is R49.99.They charge me R180 but they wnt to refund me R100.This is daylight ******* and poor customer service