I’ve dealt with this problem before.
Sometimes a customer, like a child, will push and test your limits to see what they can get away with.
When you clearly state what you will and will not offer, and they still keep pushing for more like come onnn I’ll pay you more if you do it.
No, I stick to my own guidelines and never stray from them. Even if it happens to be a great paying customer, if they continue with the same nagging I have no choice but to drop them. Sometimes I’ll even refer them to someone else who can give them exactly what they’re requesting.