If you cancel after you have been billed for services rendered, no refund will be issued and you will be charged for those submitted claims.
For example, CabMD's billing cycle ends on the 10th and 11th of every month but the claim remittance cycle ends on the 1st of every month. If you cancel on September 20th, you'll still have to pay for the remaining claims submitted from September 1st (which would be remitted the first week of October). You won't be charged after that.
You are responsible for whatever charges have been incurred. In order to treat everyone equally, no exceptions will be made.