26.— A patient, to whom a relevant scheme applies and to whom (or to a person acting on the patient’s behalf) an offer referred to in Chapter 2 of Part 2 is made, who—

(a) either—

(i) does not agree to the substitution the subject of the offer, or

(ii) agrees to the substitution the subject of the offer,

and

(b) is dispensed the branded product or a substitute medicinal product (and notwithstanding that, in the case of an offer which falls within section 9(2) or 10(2), the pharmacist could not have dispensed the branded product),

shall, if the medicinal product so dispensed is a listed item which falls within a group of interchangeable medicinal products for which a reference price has been set and the ingredient cost of the medicinal product is higher than that reference price, be liable to pay under that relevant scheme (by whatever means, taking into account the nature of the relevant scheme and how it operates in relation to that patient) to the retail pharmacy business concerned the difference (or part thereof) between that reference price and that ingredient cost and also pay to that retail pharmacy business any other related cost arising under the relevant scheme.