The Spend & Credit Alerts page allows you to enable or disable alerts for both Daily Spend and Low credit. The Daily Spend Alert will alert you if you hit a pre-set cost for the day, this is a useful feature in which to help contain your daily spend as well as alert you to any suspicious activity on the account. The Low Credit Alert will again send an email notification to you if your credit limit hits a pre-set figure so you can act to avoid any loss of service.
You can chose to use neither, one or both of these features, it is completely up to you and how you wish to manage your account. When set to the on position, for both options, you can select a suitable figure as well as a destination email for the notifications to go through to.
We would always advise you to take advantage of these features and set the figures accordingly to your expected use. For example if you don't anticipate spending more than £5.00 in a day, don't set your daily spend limit to £50.00. There is nothing stopping you from increasing this limit later in the day if you think you are likely to go over on an ad hoc basis.