Peak limit for unlimited off peak

I called your call centre on the 14th of April to reduce the additional gig limit on the sim card, and I was told that I wouldn't be able to do that, and they wouldn't be able to do that until the payment goes through on the 15th. The payment has gone through and I STILL cannot reduce the gig limit. I was told by your call centre that I can't even make the limit zero. WHY??? I don't want an additional peak limit. Please cancel it.