It can happen quickly that your bill doubles in cost without you knowing it, unless you check your airtime usage on a daily basis. This has happened to me a couple of times while moving across the country, making more calls than I realized to keep in touch and do job interviews with new prospective employers. These costs can be difficult to recover if you are already on a tight budget, especially after the financial toll moving takes. I think Koodo would be doing its customers a competitive service by sending a text (similar to the one that notifies you when your bill is due) that warn you that you've already used up your airtime or a certain amount of airtime. This would make me a more loyal customer and consider recommending Koodo as a service provider to friends/colleagues.