How to get my contracted rate?

I haven't have Comcast Business for too long.  Less than 2 months.  But in this time, I've had to make numerous calls to try to sort things out.  I would love for this to be resolved.  I first had Business 25, but were not happy.  I called again and was put into Business 75, but almost two weeks later, nothing had changed on service on my end (still 25).  Called again to confirm it would go through... promised it was being pushed through.  After several more days, I was once more assured it was okay and that the speeds should show.  After a few more days, I called again, had to re-do the contract as I was told the contract was somehow showing as cancelled in the system.  This took a while on the phone.  At this point, I feel like we are on direct speed dial, but everyone was nice and the experience was still great.  Got it squared away and we were happy campers.

Now another week + passes and I get my bill.  My bill comes in well over two times higher than what was agreed!!  More than the first two months together should be combined.  I'm told that I need to pay the bill by the customer service representative.  He would not listen that the credits aren't there.  I was so confused how he was trying to explain it to me.  First he said I didn't pay first bill.  I did.  Then he locates my payment, but still says that the bill is correct.  Can't be serious.  Neither of the amounts I ever agreed to were this high.  And If the first two months combined don't equal how high this bill is, how can it possibly be correct?  Something is not right.  I do not believe the proper contract amount is being applied.