Good for you for sticking up for yourself. You make sure you take them up on that offer if needs be, they are really good at scaring people/organisations into acting (even though the actually have no legal power at all - but dont tell the boss that
)
Now my answer to her objections would have been, politely (I don't know why I like lists so much, sorry) -
1. I already do "financially help the practice" I make your job possible by assisting you and I comfort patients so they want to come visit you - therefore facilitating financial transactions within the business. AKA helping you make money.
2. Why don't you budget for needing to pay agency/cover staff? after all it is your business and not mine. Wanna swap places? i'll pay you your holiday pay as a nurse when you take it and i'll gladly own the practice for the "stress" of budgeting for 24 days a year of your now (nurses) underpaid salary.
It makes me sick sometimes, when you actually look at how much the income of a practice is, even weighing that against insurance/memberships, utilities, staff wages, maintenance bills etc etc and how much of a fuss they kick up about the smallest of things.
My biggest grief to do with money at the moment is that my boss asked me a few months ago to do xmas cover this year, for six days strate, be able to get to the practice within 40 mintues, be sober for all the time we are on call and be phone contactable at all times i.e. answer even if your using the loo. Which is fine, I hate xmas and love working/making money (who doesn't) So when I asked, "how much do I get paid for being on call for 9 hours a day with all of these conditions" - My wonderful boss answered "paid?" So after me refusing to work for 6 days without pay, as I would not expect her to (and she most definately would not I assure you) she has since treated me like a criminal and simply made my life a misery - which is fantastic. But I refuse to budge. Phew rant over.
Anyhoo, I hope it all goes ok for you. Remember - Power to the people!