"They said that if it happens again I will be given a fine."
"They said next time there will be a fine."
"They said that if it happens again I will be given a fine."
"they said that ~" 「〜と言われた」
"if it happens again" 「また同じことがあったら」
"I will be given a fine" 「罰金にあたれる」・「罰金です」
"They said next time there will be a fine." 「次回罰金ですと言われた」