I also have a "Loyalty Plan LGCY Prem Tab" plan for 3 iPhone 6s' and 1 iPhone 6s+ with $600 subsidy each ($500 plus $100 per device instant credit at purchase) when they launched 2 years ago.
When I called in now and spoke to retension / customer relations they are saying my plan doesn't qualify and if I'd like to get a premium tab subsidy (~$500) I would have to switch to a new share everything plan.
Interestingly enough if I look at my bill 1 year into the plan they added the 'LGCY' bit (previously just called just 'Loyalty Plan - Premium Tab'). To me you having LGCY in your plan name will mean you, like me, cannot qualify for a subsidy unless you change your plan and conveniently for Rogers all of the available plans are more expensive than your LGCY one.
Anyway will try to see if I can get somewhere with Retention pre launch and your mileague may vary but for me they just gave me the option to reduce my 3 add-on lines to $35 each (from $55) as the tab expired but the primary cannot be reduced down from $99 (6GB share everything bucket - back when 6GB was considered a lot).