Hi @Dermot0
Sorry, I do not understand what is Tiered Pricing? Do you mean Smart Pricing? If you do not wish to have it on, you can go to listing->Pricing, and turn it off.
If you have it ON, you can also set a minimum price for the night - so the price will not go under that. You can also set any discounts for long stays.
It is your responsibility to check your settings.