Service Fee Integration Guide

Files to update:
1. /services/data/purchase.php - Service: 'data'
2. /services/cable/subscribe.php - Service: 'cable'
3. /services/electricity.php - Service: 'electricity'
4. /services/education.php - Service: 'education'
5. /services/betting.php - Service: 'betting'
6. /services/recharge-card/purchase.php - Service: 'recharge_card'
7. /services/transfer/send.php - Service: 'bank_transfer'

Code pattern to add:

// Apply service fee and discount
$serviceFee = calculateServiceFee($amount, 'SERVICE_NAME');
$serviceDiscount = calculateServiceDiscount($amount, 'SERVICE_NAME');
$chargeAmount = $amount + $serviceFee - $serviceDiscount;

Update transaction insert to include fee column and metadata.