Bill Increase Concern

I have just gotten of the phone with retentions who offered me M250, MIXIT TV and anytime chatter for £31. I was previously paying this price but with M125. Upon checking the pre-contract documents it says £46 but the agent told me that a £15 recurring bill credit would be applied to my account to cover this. Now that I have checked my bill, I see an amount of £126.04 which must certainly be wrong. The cost breakdown is: First Month's Package - £80.05 Next Month's package - £41 Other Charges and Credits - £19.99. The agent says that on his system it definitely says something around £82-£83 which is what I should be paying. He advised me to wait until the 28th of March but this would take me 1 day over my cooling period meaning I won't be able to exit this contract unless I pay Early Cancellation Fees. Is this cause for concern or is this simply a glitch on the system. Can a Virgin Media Employee please confirm?