Maximum extra monthly spend - reset back to "not set"?

[#1]

Can anybody explain why, having already set this to £0.00 in the past, my maximum extra monthly spend was reverted back to "not set" for August.
I switched to the 120GB package a couple of months ago, but I'm sure I checked this (I could be mistaken) because I'd heard that it gets reset after a package change. Any chance of in the future either/both:
1) keeping whatever amount the customer had already selected pre-package change
2) default to a maximum spend of £0.00

[#2]

Well, it definitely does reset on any package change.
If you check closed tickets in the 'Help and Support' section you should find a 'Service Notice' confirming the reset.
I too would like to see a default of £0.00 instead of 'not set'.  Although Plusnet do not currently offer an 'Unlimited' product you could argue that they do ('Unlimited spend' in this case).  
[Edit] Unlimited spend incorrect, see below.

[#3]

Maximum extra spend is £99, so not quite unlimited!
The default of £0 instead of not set has been brought up in other threads which we are considering.

[#4]

Quote from: Jameseh

Maximum extra spend is £99, so not quite unlimited!

Thanks Jameseh - that's a bit of a relief then (though still a bit scary for some as a potential surprise bill).
Can you just confirm, please, (simply for confirmation / clarity) that the £99 you mention is the maximum extra spend and not the maximum total spend.

[#5]

Fairly certain it is maximum extra.  Will check.

[#6]

Thanks