Up plan

Level 2
Dear TPG,

My landlord has a broadband plan with you with ID No 6278308.
We’d like to up this plan from 49.99 $ monthly to 59.99 $ monthly with unlimited data immediately.
She tried calling twice, but can’t seem to get anyone on the phone. Therefore I’m helping her with this online request. How to proceed with this inquiry?
The plan is on the name of Carolyn Dunstan (0417662442).