You should be able to see what other charges you incurred on your bill's breakdown.
VAT is charged by law.
Your base MSF already has VAT and you are not just charged for VAT without any reasons or whatsoever.
Globe provides a detailed information on the charges your account has accumulated in a month and is also specified on your bill.
For further explanation and further account details, you may visit the nearest globe customer service at any globe store nationwide, or may reach support at the following.
Twitter Hande: @talk2globe
Hotline via Globe Mobile: 211
Hotline via Touch Mobile: 808
Landline: 02 730 1000