Update: Have been on to customer services. They said that they are sending me a new sim, because the one that arrived on Saturday has a number that is linked to an existing account (someone else). How this is possible I am not quite sure.
I was trying to cancel the service under the 14-day cooling off period but apparently it is best to wait until this new sim arrives and is active, to avoid any mix ups. I have a bad feeling about this but will have to wait and see.
I also mentioned that I am not getting the service I paid for (no data or voicemail, wrong number etc.) and they said that they will look at refunding me the payment I made, once I get back in touch to cancel. They never take into account the time you are spending chasing the issues. If we say I have spent two hours either on hold, speaking to an advisor or looking into the issue generally, then where is the recompense for this?
It reminds me of when a BT sales rep signed me up for a big broadband package when I explicitly said I would think about it and did not want to go ahead. I spent many hours and phone calls trying to get out of the deal, without recompense, and I promised myself I would never ever use BT again. I suppose I am now back with BT (albeit through a 'proxy') and seem to be paying the price already!