Admin fees for paying off an 'interest free credit' account

[ReadtheSmallPrint]

I bought a TV from a high-street retailer (the only remaining national electrical retail specialist) in January. There was no 'deal' on the product, so I asked about interest free credit. I was offered a credit agreement that was interet free if paid off within six months.

I haven't had this type of agrement for several years, but have had several in the past. I have always paid them within the IF period with no problems. Date for payment was put in the diary.

Today I received a letter from the finance company telling me that if I paid the agreement off within the IF period I would have to pay a £25 admin fee. I'm pretty pissed off as I wasn't told this by the utterly fucking useless sales person when I bought the TV in the first place. Lo and behold, the 'admin' fee information is buried in the very small smallprint. There is no way I would have taken out this agreement had I known it would incur a charge - I've never known this before.

Is this sort of thing standard retail practice now?

It didn't help in the store that the sales person tried to put the deposit through on the debit card we'ld used for the direct debit rather than on our credit card, and the entire credit agreement had to be redone.

I know it's my fault for not wading through the small print. I'm just rather naffed off.