Brilliant. 
As a pp said, once they have you hooked in they don't stop. I have a similar story...
I once signed up with a monthly magazine some years ago - 2009-ish (they had reps standing in the shopping centre trying get people to sign up.) I quite fancied the magazine, so I signed up and paid £18 for the year. (£1.50 per issue instead of £2.25 or something like that.) The £18 came out of my bank account 2 weeks later. No problem. Got my first magazine the following week. Great!
About a month later, I got my second magazine. THEN shortly after, I got a phone call from the head office of this magazine asking if I would like to sign up to this special offer.... For just £50 pounds they will send me £125 worth of high street vouchers. I was like, 'what? That sounds amazing. Explain more.'
She said 'so.... It's vouchers for Debenhams, Marks and Spencers, House of Fraser, John Lewis, Harrods, Waitrose, Zara, Body Shop, blah blah blah blah blah. You will get £125.00 worth of vouchers for around 15 shops and stores.' BUT - as she went on it turns out it was £5 off this at House of Fraser, £5 off that at Marks and Spencer, £3, off off this at Waitrose, and £7.50 off that at Harrods blah blah blah. And a £10 off voucher if you spend more than £100 in 'Next.'
I then realised it was just a bunch of £5 off here, £2.50 off there and £7.50 off here vouchers on 90% of shops I NEVER go into. So I declined. 'No thanks I will just leave it. I'd never make any use of the vouchers,' I said. ' Oh, okay,' she said. End of call.
About a week later I was looking through my internet banking, just checking a few transactions. And I looked at my direct debits. There was a message there saying 50 pounds was due to go out of my account (to this magazine) the next day. So the bloody woman had actually gone and done it anyway. I cancelled the direct debit immediately and it didn't go out.
Hilariously, the 125 pounds worth of vouchers came to my house a few days later. After a few days, I started to get phone call after phone call. (I never answered they left messages,) demanding the 50 pounds - or the vouchers back. I picked up the phone after the 5th or 6th time, and told the man that I had actually refused and declined these vouchers, and didn't want them, and they should never have tried to take the money out of my account.
I said go listen back to that phone call. I said 'no, I don't want these vouchers, I will never make use of them!' And the woman said 'Okay then.' The man on the phone said 'you need to send back the vouchers.' I said 'I never asked for them, indeed I REFUSED them, and you still sent them, so YOU come get them if you want them' and then I hung up and blocked their number.
They sent me a letter threatening legal action if I didn't return the vouchers. I wrote back and said 'knock yourself out, see you in court. I didn't spend them. I haven't asked for them. I didn't want them. I wasn't interested in them.' After my letter saying 'see you in court,' I never heard from them again. Weirdly though, I did get the other 10 copies of the magazine, which were automatically set up to come out - and I had paid for them!
Also, the vouchers only had a 3-4 month deadline on them anyway! A few months later I just shredded them!