Ambrose wilson- late returns charge £2.95?

jdmt692

Grateful for any help on how to deal AMBROSE WILSON late charges, which I had no idea about until today.
I admired a dress that someone was wearing, and was told it came from the Ambrose Wilson catalogue. I ordered one online and it took a week to come, but it was faulty (twisted strap and broken clip). As they charge premium rates to phone them I sent an e-mail asking them to refund P&P charges which eventually they did. In the meantime I sent the dress back using the Royal Mail prepaid label they supplied. All dealt with I thought!!

Today (9/11) I received a statement in the post with a balance showing the dress still outstanding (£70), I logged onto the website account but this showed the dress as returned, however a new charge described as a LATE RETURNS CHARGE had been added for £2.95. I sent the dress back on 19th October, so it may have been caught up on the mail strike.
Forgive the waffle but DO I HAVE TO PAY THIS?! - I am concerned that if I don't it could affect my credit rating , has anyone else had an experience like this and what do action do they recommend? I have sent them another e-mail querying this charge but the standard reply says they are very busy and may take a while to deal with it - in the meantime, who knows what other spurious charges they may add to this one. I had never ordered anything from them before and I have not signed any credit agreement nor was I made aware of these charges, when I ordered the dress.