It shall be presumed that a reasonable number of attempts have been undertaken to conform a motor vehicle to the applicable express warranties, if (1) the same nonconformity has been subject to repair four or more times by the manufacturer, its agents, or authorized dealers within the express warranty term or during the period of one year following the date of original delivery of the motor vehicle to a consumer, whichever is the earlier date, but such nonconformity continues to exist or (2) the vehicle is out of service by reason of repair for a cumulative total of forty or more days during such term or during such period, whichever is the earlier date. The term of an express warranty, such one-year period, and such forty-day period shall be extended by any period of time during which repair services are not available to the consumer because of a war, invasion, or strike, or fire, flood, or other natural disaster. In no event shall the presumption provided in this section apply against a manufacturer unless the manufacturer has received prior written direct notification by certified mail from or on behalf of the consumer and an opportunity to cure the defect alleged.