KLM plane tickets left me with a frozen Smile

I used my Smile debit card to buy two plane tickets for £822 via KLM's website. The tickets arrived but a week later my card was refused in a shop. Smile said it had frozen the account because another £822 was due to come out and I didn't have enough money to cover it. KLM said it was the bank's fault. I could complain about KLM only through its website, but received no response. Smile has unfrozen my card but warned that, if the second payment goes through, I'll be charged for exceeding my overdraft limit. JB, Newcastle KLM has now given you an answer: for multiple purchases, airlines request authorisation from the credit card, and credit cards ask airlines to process the transaction per individual ticket. KLM says that, occasionally, banks do not properly match these transactions, leaving a double block on the cardholder's limit. I don't understand that. Smile explained it seems to be a peculiarity of KLM. Usually a payment request reserves that amount of money from your bank balance and stays there until a voucher matching the request arrives. Then the authorisation is removed. But KLM submitted two transactions for £411 each. Smile couldn't match these sums with the pending authorisation for £822 so, after two amounts of £411 had been deducted from your account, £822 was still being reserved. Smile has sent you £50 to apologise for the confusion. • Email Margaret Dibben at [email protected] or write to Margaret Dibben, Your Problems, The Observer, Kings Place, 90 York Way, London N1 9GU and include a telephone number. Do not enclose SAEs or original documents. Letters are selected for publication and we cannot give personal replies. The newspaper accepts no legal responsibility for advice.