Vox Cancellation fee

Ive been a loyal customer to Vox and never missed a single payment. I encountered bad treatment by Vox when i needed to move house. I called the company notifying of my intent to move and was advised to cancel the line. I took month to month contract since last year June and now Vox billed me R3300 cancellation fee. I made constant calls trying to figure out why the cancellation fee is this expensive as I wanted to continue with Vox to a new address. My situation was assigned to different people at Vox. I emailed, made calls requesting for payment arrangement until i was granted 2 months payment arrangement. Soon after that, i got calls from different consultants demanding that i pay whats due. This morning 21/03 i received 5 letters of demand on email from this company threating me to take a legal route on this matter. I would never recommend this company to anyone, ive been harassed daily by Vox.