Good ways of learning to swim?

[shouldknowbetterbynow]

My children have been going to swimming lessons for 18 months and still can't swim. Can anyone recommend intensive or residential courses that work? I don't mind travelling as could tie it in with Easter..

how old are they?

I think an intensive week (or two) is better than once a week. My ds (then 6) did a course last summer - half an hour every day for two weeks and cracked it. Our local pool runs courses in the school holidays. Where do you live? Previous to that he'd been doing lessons once a week with the school. I must say I'd be a bit if I'd been paying for lessons for 18 months and they still hadn't learned.