Scout Borromeo branch overcharged me for P2,140 for medicine purchases made last March 2020. - Consumer Complaint for Mercury Drug - HEAD OFFICE

I returned to the said Mercury Drugs branch days later to complain and they confirmed the overcharge. Instead of directly reimbursing me, the branch cashier, Nina, issued an invoice receipt indicating a gift certificate for P2,140 dated 14 March 2020. She advised me to just present said invoice receipt to claim the gift certificate value when making future purchases. They also took my original receipt of medicine purchases proving the overcharge. I was only able to present said gift certificate-cum-invoice receipt to the Sct Borromeo Branch today, 21 March 2021. But the cashier, Ms. Pedralvez, asked for a copy of gift certificate. I said the Cashier Nina only gave me the invoice receipt which served as gift certificate. In additon, Ms. Pedralvez said they cannot honor the invoice receipt since it was issued last year. Yet, the invoice receipt indicated that it shall be valid for FIVE (5) YEARS FROM DATE OF PERMIT TO USE. I also argued that gift certificates usually don't have expiry dates. Ms. Pedralvez then said she will have to discuss this with Cashier Nina who is on night shift. I am worried that Mercury Drugs Scout Borromeo will not honor this invoice receipt-cum gift certificate.