Sky won't let me use MoneySavingExpert link to save money. Is this fair?

Fatherfaff

So I tried to sign up for Sky Broadband & TV by using MSE's price comparison checker and picking a deal that offered a £100 voucher. Halfway through the process of signing up the webpage informed me I couldn't go any further online and had to ring them. I rang them and they said "we have found an (Sky) account associated with your address". On quizzing them they told me the account holders name but said the account was no longer active but that I wouldn't be able to use the MSE £100 voucher deal as the voucher didn't come from them. I checked the history of my house (which I own) and the account holder sold the property in 2017. Since then it has always been on Virgin Media. The best Sky can offer me is the deal without the £100 voucher. Is this fair? Is there a data breach also - revealing a customer name and tagging properties for over 7 years? Is there any way I can get them to un-tag my address so I can take advantage of the MSE offer?