Don't feel so bad TWB. To get the calls and texts I pay £5 per month making £11 in total so you're still up on the deal.
On an interesting side note, I got my first bill from Three business today. The billing date starts from 7th of the month and as I'd started on 2nd there were an extra five days' worth to pay, i.e. an additional £1.
I also had an additional 6p to pay on the sim that I put in the phone for three texts. I must have used the wrong sim for texts at first before locking it out, but it looks like Three is still using the old 1,2,3 PAYG tariff for business. Retail charges are 10,10,5 for minutes/texts/data MB.