I just managed to get them to drop a totally unreasonable £12 charge - actually the 2nd over the same thing, and I don't think the first was really fair but couldn't be bothered until the statement arrived this morning.
In June I bought a bookcase and a playgym for my new baby (born in May). My storecard has had a direct debit set up on it for minimum payment, but normally I use it occasionally, no more than once a year, and settle the bill in full. This time I was probably a bit distracted with baby and all, and also hadn't realised that they've changed my account number, so direct debit doesn't work. So, forgot bill until it was too late, noticed and thought, ah well, minimum payment will go by direct debit.
Then I got the next statement and a couple of weeks later a nasty letter. Rang up because letter dated 15 August was about statement with due date of 23 August. I get paid on 15th of month so had set up a full balance payment to go out that day, would have gone through after letter but in time to pay statement. Phoned, was assured it was ok, and oddly, letter quoted my old account number not the current one.
Today, I got the new statement, payment went through on 17 August but another £12 charged on 15th. Rang up and spoke to someone who insisted it was charged because I hadn't paid minimum payment installment (all of £5.26 ffs) immediately on previous statement (no, I waited until payday and settled it all). I kept pressing on the point that the statement due date was 23 August and I'd met that and paid one penalty charge already. Finally she said she'd put me through to Collections for them to "explain" to me, and I said I didn't want an explanation, I wanted them to waive unfair charge.
Anyway, she didn't have authority so I did let her put me through, and when I explained to Collections, they didn't try to fob me off, they said ok, we'll clear that and the interest, 75p, off your account.
The phone call will have cost me, but at least I've saved a little over £12 and stood up to this scam.
IKEA charges to pay with anything other than their storecard, so I'm still debating whether to cut up my card (and write letting them know why) or not. Particularly as the original missed payment wasn't actually completely my fault, and was under half the charge for not making it. It's just it all takes time that's hard to find with a small baby - fortunately my son was being unnaturally quiet at the time.