The burden would be on you to research and find out if they were unlicensed when conducting repairs. Then, provided you are still within the statute of limitations, you can still file in tort, and seek damages based on the code that they are in violation of by claiming not just that they failed to perform but that they materially misrepresented by failing to inform as to lack of license. This is not a 'continuing tort'; a continuing tort is where damage continues to exist, such as where your property is being infested by groundwater that your neighbor is failing to repair. This is completely unrelated to that theory of law.
As your initial complaint you do not need full detail but you need some specifics. I would suggest that you visit your local county law library and obtain a template from the law librarian of what a typical complaint should look like and base your filing on such templates.
I am unclear as to why you'd want mediation--that is both expensive as it is in addition to court and non-binding on parties. Typically mediation and arbitration clauses are added to contracts to make litigation so expensive as to keep parties from filing, which is why avoiding them is generally in your best interest.
PS. As it is very late here I will be logging off to get some rest. Should you have more questions I will be back in the morning and will try to help but there may be a delay with my responses. Otherwise, if satisfied, kindly do not forget to positively rate. Thank you!
PPS. There are no forms here, you'd need to create documentation from scratch, but you can use your local county law library for templates as I suggested above.