How to regulate overpay of a water consumption?

When it comes to customer service subscriptions, you can:
 

1. if the amount of overpayment is less than the amount of the invoice, it is necessary to pay only the difference per invoice and if the overpayment is higher than the amount of the invoice, do not pay invoices up to the amount of overpayment
2. the specified amount of the account can be deducted by the user for the subscription and the difference is payable (if the subscription is less than the invoiced amount) via request form
3. fill out an overpay reimbursement/cross-entry request form