Waiting for 3 weeks for a reply to my enquiry into trading in my old SP PVR

I wish to trade in my old SP PVR as offered on the DSTV website. The trade -in offered by DSTV calls for one to send a SMS to 42506 and reply YES. I have sent perhaps 12 over the past 3 weeks and get no response. I spoke to three consultants and they do not know what I am talking about. I even E mailed them with no response. Is the rot is spreading to even private organisations? Here is what they advertise.............. This trade-in deal is NOT available at our service centres or agencies. If you’re interested in this deal, please SMS the word YES to 42506 and we’ll call you back. This trade-in deal requires a credit check and is only available on debit order.