If your service is marketed as 'Prepfully' and payments show as made to 'Prepfully' in customers' card/bank statements (That's very important as @smca highlighted) then I wouldn't believe a claim that the chargeback was accidental.
Likewise, if your service is indeed a "1-1 mock interviews / coaching service" then my reply to any claim that they "forgot they used the service" would be: "Pull the other one".
When they promised to withdraw the chargeback did they actually do it (you might not have any way to know)? My guess is that they didn't.
IMHO these were dishonest customers, and I would blacklist them to avoid repeats.
Now regarding your question specifically I think the only way is to understand why you lost and to beef up your evidence, processes, T&Cs, etc as needed. Unfortunetaly I do not have much insight in that.
Likewise, if your service is indeed a "1-1 mock interviews / coaching service" then my reply to any claim that they "forgot they used the service" would be: "Pull the other one".
When they promised to withdraw the chargeback did they actually do it (you might not have any way to know)? My guess is that they didn't.
IMHO these were dishonest customers, and I would blacklist them to avoid repeats.
Now regarding your question specifically I think the only way is to understand why you lost and to beef up your evidence, processes, T&Cs, etc as needed. Unfortunetaly I do not have much insight in that.