SD PVR swop facility

I had an Explorer and a sd pvr on my account. About 2 months ago I asked to add another explorer to my account as xtra-view. The call centre said that they would have to replace it with the sd pvr. I asked them that if they do that, would I still be able to swop my sd pvr for an explorer and it was told that I could do so and they would get them to call me regarding the matter. 3 weeks passed and no one contacted me. I again sent sms regarding the swop. I was then contacted and I told them that the pvr had not been used for a while, but they said it was not a problem. The lady was going to contact me the following day to finalise and also give me the names of installers in my area. There was no call the following day, so I contacted On-Air again the following day and was told that the pvr had to be active and I would have to contact Multichoice to confim this. On calling them, they said that the pvr was inactive which means that they could not do the swop. This was not at all what was told to me before. How do we pay for something and then it is expected to just throw it away???