Holiday trouble

We are going away on a holiday and we want to take my partners son.

Last time we went I messaged the baby mama and she Ignored it, along with my other messages. I would talk to her in person but she refuses (I guess it's because I'm the other women) 🙄

Anyway my partner rung the baby mama and she said no, my partner is so upset because it's his son too and his son gets so upset when he can't come. He thinks it's because we don't want him too but that's not the case.

Do we say we will take it further?

What can we do?

He always goes on holidays with his mum and nan etc so why can't he go with us?