What would Alexander Graham Bell say?

My letter to Vodafone:

I have been a Vodafone UK PAYG customer for years and years.
Only recently I was told that the way vouchers worked was changing, at the end of a month the voucher would expire and I would need a new one.
As I use my phone only for emergencies I decided to shop around for something cheaper, finding GiffGaff who would do a rolling monthly deal for £5 a month.
So far so good.

19-9-13 8.10am
I go to Vodafone live chat and ask for a PAC code and help to unlock my phone for use with GiffGaff.
 The helpful customer service lady gives me the PAC code straight away, then rings me to take my Visa details to charge me £20 for the unlocking.
Again, so far so good.

Yesterday on the 23rd, 4 days later,  I receive an e-mail, Vodafone have no record of my account and cannot proceed with the unlock???
So, I ring Vodafone and speak to Cambel.
No, he cannot help me, he has no record of my account, I have done everything wrong, this is all my fault, the best he can do is give me £10 refund, no - I cannot speak to a manager, no - he does not know the ombudsman number, the best I can have is a ring back.
So, I explain, check your records, when I contacted Vodafone, no one explained I could not do what I am trying to do...after all, I just want the phone unlocked and I have been charged for it, if you cannot accomplish this service refund me the money and I will go elsewhere.
No, he will not do this, I should have known I cannot do this, it is my mistake. (I seriously think you shouold listen to the call which I am told was recorded!)

So, I get a call back from Gillian the Manager.
No, they cannot help me. She has looked at me account...but hang on, Cambel told me I had no account, that no details of my contact with Vodafone were there...but Gillian tells me she can read them on the screen as well as the conversation I had on the 19th!
So, unlock the phone or give me my money back. No, they cannot do either!!! WHAT!

I've paid for a service, Vodafone can't accomplish this, and won't refund the money!
So I ask them to contact my nearest store, just ring them, tell them to unlock it, I've paid, job sorted...No, we cannot do that.
This is all for £20. Really! You cannot refund £20. Is this a joke?

By now I am very angry. Is this nothing short of ridiculous and unacceptable?
The best Gillian can offer is I go out and buy another sim and then she will refund the money?
Why do I have to go through the hassle of all this for what is not my fault.
Cambel told me I should have known better, but as I explained, I am not familiar with how phone companies work, I thought you were and I would have been told.
Apparently this is all my fault, my mistake, and Vodafone, this huge company are completely unable to do a simple unlock on my phone or refund me money without me having yet another sim from Vodafone.

 I am used to giving praise where it is due, as well as telling people when I run up against sheer blind,  bureaucracy.
I have never come up against such a ridiculous system and unhelpful people calling themselves 'customer service'.
I will be very happy to tell everyone I know, blogs and facebook just how I have been treated.
Just to have a simple unlock performed that I could have gone into town and had done for a fraction of the cost you are charging, but I foolishly thought I should ask Vodafone.

It's only an old Sony Ericsson, I could have bought a 2nd hand unlocked phone on eBay for less than £20
Please thank your staff for such a horrible ordeal that has left me very, very angry and to date, still with an unlocked phone and £20 out of pocket.