To my understanding the sentence 「何も悪い事は聞いた事がありません」means something along the lines of “I have’nt heard any bad things”. What I’m confused about though are these words: 「何も悪い事は聞いた事がありません」As far as I now all three of these mean “thing”. So why is this word used three times in this sentence, what use does each one serve?
This modifies 悪い事 and means "any/all"
You said it yourself "bad things" so 事 here can be translated as "thing"
This is part of the [past tense verb]+ことがある construction meaning that there was a time where the action occurred or that the speaker is expressing their experiences. This manifests itself in your translation "I haven't heard any bad things" which contrasts something else like "I didn't hear any bad things"
Putting it all together makes something like "I haven't heard any bad things" or "I've never heard anything bad"
ことがある is a set phrase that when combined with the past tense (た form) of a verb, means "have had the experience of doing V". The word こと here doesn't have any meaning in and of itself; it's a nominalizer that turns the verb phrase into a noun so that you can talk about it as a concept:
I didn't hear a bad thing.
I haven't heard a bad thing. (Lit.: the act of hearing a bad thing doesn't exist)
The first こと in this sentence literally means (intangible) "thing."
Finally, 何も means "not any" or "nothing." Without it, the sentence could be construed to mean "I haven't heard the bad thing." With it, it becomes "I haven't heard any bad things." 何も doesn't mean "thing."