When someone goes to the trouble to tell you “no” as honestly and as politely as they can or care to be, accept the answer. Period.
It is neither polite, gracious nor respectful toward that person to keep pushing the issue.
What it is, is self-centered and self-absorbed.
Who are you to argue with their boundaries, standards and priorities?
Do you think they were put here on this earth with nothing better to do than wait on you hand and foot?
You are not the center of the universe.
No one owes you their time, attention or energy.
No one even owes you politeness or graciousness, for that matter, and especially not when you don’t extend good manners or graciousness yourself in the first place.
Those things are gifts and it is each and every person’s right to decide upon whom they will bestow those things.
They give what they choose or are able to give and you should have the good grace to respect that and not demand anything more as if you were entitled.
When you’re paying for that person’s time, then and only then do you MAYBE have any say-so as to who and what they give their time and attention to.
Get conscious about this.
Take responsibility for how you treat others (givers are conscious and grateful; takers are self-entitled and think everyone owes them).
Be mindful of your manners and what kind of imposition you may be creating.
Stop thinking about only yourself.