They charge $95 even if you wish to go from DSL 16 to DSL 25. It use to be only $25 within the same catagory (ie. basic, FTTN), so going from 16 to 25 was $25. Now it's $95 each move you make. I can't seemt to find the FAQ anymore when it was only $25 for each change within catagory. So, just in the last couple of days the fees went up again!
They always charged the $99 fee when upgrading from any of the FTTN tiers to another.