Account not being corrected

I did an upgrade and made sure that the phone was blocked. A month later I receive an account of R2400. I immediately phoned and visited the outlet. I was informed by the helpline I did not block the phone. Two different operators then blocked it for me.The outlet manager immediately raised a query as he confirmed that he blocked the phone during the upgrade. The query was raised on 16 June 2015. Up to date 10.07.2015 I have had no feedback about my account. When I checked on my unbilled account for this month it was already R645 instead of R330. The outlet manager was contacted and he will call me back as soon as he knows what the problem is. We have no way to protect ourselves against a person who says that we did not block the phone if we know we did all we can. This is not fair.