Uncer*****y of contract amount.

I have recently switched to a more affordable package with higher data and talk minutes but have been billed more that 4 times the actual amount on the first month. when this was queried I was told that the specials where not deducted. the following month it was just under 3 times the amount and this time no concrete explanation given. I have recalled my debits due to uncer*****y of contract only to have my business number which I had for 21years blocked.