As I finger a lovely white waffle robe, I can hear a little voice at the back of my head, like a radio turned down low. Don’t do it. You’re in debt. Don’t do it. You’re in debt.

But quite frankly, what does it matter now? It’s too late to make any difference. I’m already in debt; I might as well be more in debt. Almost savagely, I pull the dressing gown down from the rack and put it over my arm. Then I reach for the matching waffle slippers. No point buying one without the other.

The checkout point is directly to my left, but I ignore it. I’m not done yet. I head for the escalators and go up to the home-furnishing floor. Time for a new duvet set. White, to match my new dressing gown. And a pair of bolster cushions.

Every time I add something to my pile, I feel a little whoosh of pleasure, like a firework going off. And for a moment, everything’s all right. But then, gradually, the light and sparkles disappear, and I’m left with cold dark blackness again. So I look feverishly around for something else. A huge scented candle. A bottle of Jo Malone shower gel. A bag of handmade potpourri. As I add each one, I feel a whoosh — and then blackness. But the whooshes are getting shorter and shorter each time. Why won’t the pleasure stay? Why don’t I feel happier?

“Can I help you?” says a voice, interrupting my thoughts. A young assistant, dressed in the Octagon outfit of white shirt and linen trousers, has come up and is looking at my pile of stuff on the floor. “Would you like me to hold some of these while you continue shopping?”

“Oh,” I say blankly, and look down at the stuff I’ve accumulated. It’s actually quite a lot by now. “No, don’t worry. I’ll just. . I’ll just pay for this lot.”

Somehow, between us, we manage to lug all my shopping across the beechwood floor to the stylish granite checkout point in the middle, and the assistant begins to scan everything through. The bolster cushions have been reduced, which I hadn’t realized, and while she’s checking the exact price, a queue begins to form behind me.

“That’ll be £370.56,” she says eventually, and smiles at me. “How would you like to pay?”

“Erm. . debit card,” I say, and reach for my purse. As she’s swiping it, I eye up my carrier bags and wonder how I’m going to get all this stuff home.

But immediately my thoughts bounce away. I don’t want to think about home. I don’t want to think about Suze, or Tarquin, or last night. Or any of it.

“I’m sorry,” says the girl apologetically, “but there’s something wrong with your card. It won’t authorize the purchase.” She hands it back to me. “Do you have anything else?”

“Oh,” I say, slightly flustered. “Well. . here’s my VISA card.”

How embarrassing. And anyway, what’s wrong with my card? It looks all right to me. I must call the bank about this.

The bank. Meeting tomorrow, with Derek Smeath. Oh God. Quick, think about something else. Look at the floor. Glance about the shop. There’s quite a big line of people now, and I can hear coughing and clearing of throats. Everyone’s waiting for me. As I meet the eye of the woman behind me, I smile awkwardly.

“No,” says the girl. “This one’s no good either.”

“What?” I whip round in shock. How can my VISA card be no good? It’s my VISA card, for God’s sake. Accepted all over the world. What’s going on? It doesn’t make any sense. It doesn’t make any. .

My words stop midstream, and a nasty chill feeling begins to creep over me. All those letters. Those letters I’ve been putting in my dressing table drawer. Surely they can’t have. .

No. They can’t have done.

My heart starts to thump in panic. I know I haven’t been that great at paying my bills — but I need my VISA card. I need it. They can’t just cancel it, just like that.

“There are other people waiting,” says the girl, gesturing to the queue. “So if you aren’t able to pay. .”

“Of course I’m able to pay,” I say stiffly. With trembling hands I scrabble in my purse and eventually produce my silver Octagon charge card. It was buried under all the others, so I can’t have used it for a while. “Here,” I say. “I’ll put it all on this.”

“Fine,” says the girl curtly, and swipes the card.

It’s only as we’re waiting silently for the authorization that I begin to wonder whether I’ve actually paid off my Octagon account. They sent me a nasty letter a while ago, didn’t they? Something about an outstanding balance. But I’m sure I paid it off, ages ago. Or at least some of it. Didn’t I? I’m sure I. .