Disrespect

We bought a dstv decoder at Pep Protea Glen, upon arrival the installer said the decoder wqs faulty, we returned it only to be told that we had tempered with the decoder. The store manager did not even test the decoder to see if really it was faulty instead said we would rather just go else to get the decoder she took the decoder back gave us our money and the voucher that was torn off from the receipt by tge installer. There was no courtesy to even ask how she could assist. How can an adult temper with some thing they bought with their own money?