Admin error?

I've been a Vitality member for quite some time and have an active Sterkinekor rewards programme with a number 1500***x1994 that I still used on the 11th October 2020 to buy a ticket. On the 18th Oct 2020 i tried to buy a ticket and I was informed that the number is inactive. I called the week and was informed that the above number (that still worked a week ago) was inactive since 2017! After spending more than an hour with both Discovery and Sterkinerkor on the line I was made out to be the **** and in the end ended up with a different Vitality number. I am not happy with this as the number is very long and now have to keep my phone with me if I need to make bookings for the number. I'm not happy with this as it's clearly and administrative error on Discovery's side and want my old number activated as how can I use a number to make a booking in 2020 but according to Discovery it was inactive since 2017. Fix it!