It is not legal to look back at non-flying duty days and assign as "OFF"

If you are not free from phone calls, call outs or any possible duty assignment, you are NOT off.

If you can't have a beer, you are not free from duty obligation. Your employer is in clear violation CFR's.

Most worrisome is your potential exposure. If an accident or incident were to occur with fatigue being a factor, don't think for a second that you wouldn't be held accountable for not ensuring that you had 13 days OFF per quarter.

I would recommend you start formally requesting days off via email and bcc your personal email account. Responses should come from the company IN ADVANCE notifying you of assigned days off.

If this isn't reasonable to them, then what will be? They operate so close to margin that they can't schedule 4.25 days per month off? Where else are they misinterpreting the CFR's?

CYA, the most important acronym in aviation.