Dstv put my money on the older non functional decoder on my profile now they can't reverse.

We used to have an older decoder, then we decided to buy a new decoder. We used it for more than 6 months then this December when we paid the subscription they actually activated the oder one which we told them to remove form our profile mire than once. Now the told me that they can't take the money from the old one and put to the new one. My question, is this the lack of knowledge from the call center people or they are just pulling our legs. I am still feeling.tje pain of loosing R320 for nothing. Please help. ***