Ridiculous cancellation fee methodology

Is it just me, or is Vodacom's cancellation calculation methodology highly flawed? How can they justify charging 75% of the full remaining contract? So if I've had a Vodacom device for the full contractual term, renew the contract and then want to cancel shortly afterwards, I'll be hit with a massive cancellation fee, and for what? The 'future' use of data/airtime? The admin involved in getting me off the system? What are we paying for in that fee? It's ********, and I think the CPA should look into it.