why can't I do a simple dial-up to broadband upgrade on-line?

[#1]

Hi stuck,
It looks like the account change at the end of January has added an incorrect charge to your account. I'm very sorry about that. I'll take it up with our development team shortly.
Unfortunately as the payment is going through there's nothing I can do at the moment, however as soon as it's clear I can either refund you £5.99 or alternatively credit your next payment so next month will be free? It's up to you, however I'm sorry there's nothing I can do to cancel the charge.

[#2]

Based on my limited experience of Plusnet systems I suggest minimal intervention will be the most effective route, i.e. leave the automated bits alone and correct this error by manually giving me a credit.
However, you're staff, you know how things work so if your judgement is that doing something different would be better, then do something different.
I don't mind how it is resolved as long as it is resolved correctly.
stuck
PS you are going to update the Ticket aren't you?  You don't want someone picking it up and not knowing about this exchange in this thread, complicating things further do you?

[#3]

I've added a credit for you and replied to the ticket so there should be no confusion over what's happening. I'm sorry that the double charge happened.