Paying lump sums off a variable mortgage

I have my AIB mortgage account under my 24 hr banking profile by adding new accounts as you say however i am unable to transfer any money from my current account to the mortgage account.

I was in the same situation and was also told I couldn't just make an on-line transfer whenever I felt like it to pay off the mortgage. They told me I had to send in written instruction each time. I never tried ignoring that advice and attempting an on-line transfer.
 


I didn't think banks were allowed to penalise you for making extra payments off a variable mortgage unless you changed the actual terms of your mortgage. What exactly were the charges for?