La Pino'z Pizza - Asking for payment even after paying incash

Although no loss has yet occured but I'm afraid I might fall into an abyss . I ordered a Pizza from La Pino'z app. The in-app payment method had a glitch while paying through the debit card and said "the payment was received". But when the Pizza delivery guy came he told me that I have to pay because the payment wasn't received and that if it were received the bill would have PREPAID written on it and it sure wasn't. So, I called the Pizza store and the receptionist confirmed that I had to pay the delivery guy. So, I paid him *** rupees in cash ** days ago and today I received a message Requesting for Money, asking me to pay within ** hours to avoid any sort of "Legal Action". So, right away I called La Pino'z and the receptionist only acknowledged my problem but provided no solution and I received the same message once again. I don't understand what to do. It seems it's some kind of extortion. Please help.