Installation voucher installors

I purchased a dstv decorder with an installation voucher today. When I contacted the call centre they advised me to go to the website to see for installers in my area. When i called the installers a total of 5 they all said they do not do installations with the dstv vouchers. I called the call centre and all the agent said was try another city. How can dstv have installers on their list but they do not proivide the service you require. This is disappointing. And if this is he case then why does dstv sell the decoder with the voucher. Please provide me with at least a decent list of people who is willing to instal my decoder. Terrible service from dstv and multichoice.