Paul there something not right with your pump...
I haven't got my manual to hand, so I going of the top of my head here..
There isn't a way to set a customised bolus max, this is factory setting of 50 units if I remember rightly..
The only place I can think of a bolus being set, is the increments for the quick bolus, when you use the two rocker buttons on the side of the pump, where you press and hold either button to get the bolus to kick in, then use the other button to press how much you want, i.e if you got it set at 0.5 and you want a bolus of 2 units you press 4 times...
The W8, yep is something being cancelled, this could either be a bolus (any of the 3 you set up) and/or a temp basal rate so double check what it's actually telling you, if you've got a tbr and a bolus programmed in, it will alarm with each cancellation..
My prime is set at 25 units, to ensure that I can get all bubbles out, I was told originally not to worry about the odd champagne bubble, but even these with my insulin sensitivity can cause me problems, so need to get them all out..