It is a condition for invoking the warranty that the end user, within the Warranty Period, submits a written complaint no later than 14 days after the defect was discovered or should reasonably have been discovered. The complaint must be sent to Caball Therapy Systems (CTS) or to the authorized Caball Therapy Systems reseller from whom the product was purchased. The complaint must be accompanied by valid documentation, such as an invoice, proving that the product was purchased either from Caball Therapy Systems or an authorized Caball Therapy Systems reseller. For the warranty to be valid, the product’s serial number must be clearly visible and accessible. Warranty claims without a visible serial number will not be accepted.