Not sure whether it's merely coincidence or not (do they even use the same infrastructure?) but on Tuesday this week (3/6/08) I had all kinds of problems registering my phone with Vodafone. The phone would sit either perpetually "searching..." or would display "Vodafone UK" but then fail to send or receive calls or any kind of data. This was over a 60 mile area at least.
Eventually in the evening I called Vodafone CS who told me they were having "widespread problems with connectivity over the south coast [of England]", but I haven't seen mention of it elsewhere. The operator told me it was limited to 3G networks, and sure enough switching back to GSM-only solved it. Wednesday morning and everything was fine again.
"Every customer on a pay monthly contract over £40 or higher will automatically get 500mb of inclusive mobile internet access as part of their deal"
Just called up Vodafone to see whether I could now switch off my £7.50 data bundle, hoping that I would have an automatic 500Mb bundle starting today (I currently pay £44+VAT/month just for the tariff). However, to get this I would need to extend my contract for six months, and Stop the Clock suddenly becomes a £5 chargeable extra (was included in my contract for free).