Stupid debt surfer mistake cost me £1,000s & I bet you’re making it too, how to avoid it in four steps

FOR the past 10 years, I've had a £9k black cloud of debt looming over my head... until now. I've FINALLY paid it off this month, but I'm not popping the bubbly to celebrate, I'm actually kicking myself - I've made a really stupid repayment mistake which has cost me THOUSANDS. When I was 22,...