That 'archaic' DSL is a good starting point for negotiation, it doesn't matter if it is slower or faster, a good or bad value you have to be ready to call your or their bluff.
Other thing that matter is your payment history, if you pay on time or not. I recently tried to negotiate faster speeds for a business client and TWBC said NO! In front of me was the two month unpaid bill... not a good idea to negotiate under those conditions.
I'd love to play poker with you