Early migration

I decided to migrate from the Smart Large package to the Uchoose Flexi 500. I confirmed the migration on the 29th of April. The consultant that assisted me informed me that the new package will start on the 1st of May, therefor I must use all my remaning minutes, data and sms by the 30th of April. This morning on the 30th of April to my dismay the, I was already migrated to the Uchoose Flexi 500. I therefor lost about 40MB of data, 60 free minutes and a few hundred sms's which I could have utilised today. I contacted the call centre and they advised me that the migration was processed early, and this happens sometimes. But this leaves me in deficit in terms of my airtime balance, since I am being charged from today using next months airtime allocation. Please advise what happened to my free minutes, data and sms's that I already paid for and that I cannot utilise because of your systems early processing.