Many thanks and top notch suggestion! I spoke to Elizabeth and Pamela at Halifax Customer Services. As you rightly advised, the reason for reduction was lack of recent use. It is their standard practice to reduce to £500 in case I had decided to 'abandon' the card and it fell into the wrong hands. I had to 'apply' for an increase in credit limit there and then over the 'phone by answering several questions. Unfortunately, my application was instantly rejected because my limit had only just been reduced. Apparently, there is a six months waiting period before you can apply for an increase following a reduction. I do have a right of appeal but I would have to do so in writing.