Since no one else has chimed in I will give my 2 cents worth. In my experience, the ESP providers are going to require anything you want to do in writing. Also, since over a year has transpired since the contracts have been initiated your refund will be heavily prorated if they allow a refund at all, especially if you have filed any claims.
Start with the finance department that sold you the contracts, but don't expect too much help from them, they have already received their 100% commissions and spent it long ago.
If you have any paperwork at all, somewhere in the fine print the details of the cancellation process should be stated somewhere.
Do not be surprised if you can only get half your money back. If the refund is on the smaller side, you may opt to just keep the plan, that is if they will tell you up front how much they will refund.
You can be sure they will do everything to make this process as difficult as possible for you and it will take many months to conclude the process.
Good luck