Can my commissions be delayed and quota reevaluated one week before payment was supposed to be made?

My company didnt issue commission plans until March this year. As a result they paid a recoverable draw for Jan and Feb commission pay periods. I received and accepted my commission plan in mid March, and now today, only one week before I was due to receive my commissions for Jan, Feb, and Mar I received a note informing me that they will be continuing with their recoverable draw for Mar sales as well. Additionally they will be removing all of our commission data from the reporting tool while they decide to reevaluate the deployed quotas. They had found some "inconsistencies in the numbers" and want to evaluate any impact that may have on commissions. Since I'm having a great year, this worries me on a couple levels. Most importantly because it turns what was supposed to be a $50k commission check into a $6500 draw payment.

Can they really decide to not pay me for commissions earned with less than one week's notice? Do I have any right to demand payment? Or sue for interest on the amount?