Unwilling to refund overcharged amount

I cancelled my Telkom Mobile account in March and was then billed almost double my monthly fee. My account was already out of my 24month contract period so they should not have been any reason to over-bill me. I spoke to a consultant on the 8th of April and logged a refund request, ***, but nothing has happened as yet. The billing cycle has been closed for April and I wasn't refunded my money. This is theft, plain and simple. I cannot believe that his cannot be resolved as my account has been closed and Telkom still owes me money!!!!