Excess charges includes your Share-a-Load, promo subscription and other charges on top of your bill. This occurs whenever you have exceeded your Monthly Service Fee (MSF). You may refer to your Globe Postpaid Bill for the breakdown of charges. Kindly visit this link Bill Tutorial | Billing | Postpaid | Help and Support to learn how to read your bill.
To manage your data usage, I suggest you to download the My Data Manager app available on Google Play and App Store.