One other thing - Supanet told me in a letter that they would not give me a MAC code until I paid them £39.99 - I thought this was way out of line. I have this in writing and have asked Otelo if they want to see it.
Having that in writing sounds great! Please see it through!
I've been working for a large British telecommunications (AHEM) company for five and a half years, yet in all that time I've never heard of Otelo or Cisas, which is very interesting! We're well aware of the Ofcom regulations, of course. (I've generated MACs every other day for a good few years.) It sounds like it might be worth threatening Otelo with reference to Ofcom if you have trouble getting anywhere...
Certainly, no ISP has the right to charge for a MAC, or to deny one based on a minimum contract term. They can argue that you owe them £x.xx, but they still have to provide the MAC on request, minimum contract or not. Sic 'em!
(BTW My current internet connection is a very unreliable (yet surprisingly sometimes great) mobile USB job, since I don't yet have a new phone line after moving. £25 for 7GB, to be used within 30 days! Ouch! Then you get charged £1 per Megabyte! Bar stewards! Another few weeks, all being well... )