3 wei for an NFT mint

Smart Contracts
#1

I recently created a SC and a Dapp for minting my NFTs.
Each NFT is set at 5 MATIC for someone to mint to their wallet.
I have had friends go through the process of minting one of my NFTs and its costs them 5 MATIC
Somehow, 3 people have managed to mint NFTs from my contract at a cost of 3 WEI each.

How is this possible? And what can I do to fix it?

#2

In case of any doubts regarding developing your NFT minting website or app? Do reach our team at Hivelance, a NFT minting website developing firm who can help you to fix this.

Regards,
Steve