There is only so much you can do through negotiation. You have been delivered an RPI + a bit rise for the next 3 years and your reps would be doing the crew community a disservice if they did not give you all the right to take time to reflect on that deal.
You now vote. If the result is acceptance of the deal, then the pay round is complete. If you vote no with a heavy majority, Amicus will ask its membership what it wants to do next up to and including full industrial action in a position of strength. 60-40 or 40-60, it is a loose loose.
Good luck in whatever you choose.