6. With respect to the services referred to in point (d)(i) of paragraph 1 of this Article, point d(ii) of paragraph 1 of this Article only as regards payment transactions through a credit card and point (d)(iii) of paragraph 1 of this Article, Member States may determine a minimum number of operations for which credit institutions can only charge the reasonable fees, if any, referred to in Article 18. Member States shall ensure that the minimum number of operations is sufficient to cover the personal use by the consumer, taking into account existing consumer behaviour and common commercial practices. The fees charged for operations above the minimum number of operations shall never be higher than those charged under the usual pricing policy of the credit institution.