60 days from the date of issuance. 7. Means of filing complaints with the service provider: The service provider shall retain copies, in paper or electronic form, of the issued invoices, according to the period specified in this document, bearing the burden of proof for the validity and accuracy of the invoiced amounts in case of any dispute. 8. Service providers must provide the user with proof of receipt of any payment amount, indicating the type of service paid, its number, payment account number, and the amount and date of payment, and retain the document for the duration of the related invoice. 9. The user has the right to object to the service provider’s charges for any service(s) which he believes was/were not used by his/her number, or that he requested it. In such a case, users do not have to pay the charges objected to until the objection or the ensuing dispute has been settled but must only pay the undisputed amount of the invoice, by the date of payment referred to in the invoice. 10. The user has the right to object to the validity of any charges included in the service provider’s invoice within (60) days from the later date between the issuance of the invoice or the date on which the user became aware of the invoice if it is not proven that he was aware of it at the time of its issuance. The service provider must prove the user’s awareness of the invoice. 11. The user shall not be responsible for paying any previous charges that have not been invoiced correctly, in whole or in part, except in the following cases: a. The amounts are valid for periodic or non-periodic charges, provided that they are invoiced and claimed to the user within (60) days from the due date. b. The amounts are valid for international roaming charges, if invoiced and claimed to the user within (60) days from the date of use. 12. If a user so requests, the service provider may conclude a written agreement with him to pay in instalments, as may be appropriate and enforceable, provided that the service provider ensures that the following conditions are met: a. the amount of one instalment for the charges in paragraph number 11(a) of this Article does not exceed the value of the credit limit for the period in question, unless the user wants to pay a higher amount. b. the amount of one instalment for the charges contained in paragraph number 11(b) of this Article does not exceed twice the credit limit value for the period in question, unless the user wants to pay a higher amount; c. the amount of the instalment does not fall within the value of the credit limit of the invoice in which it is included; 17