How dos pre ordering with tesco work? call of duty black ops issue

Does anyone have any idea how pre ordering from Tesco works? Do i get charged when i pre order it or a couple of days before it gets delivered?

I pre ordered Call Of Duty Black ops, on Tesco entertainment ages ago, im sure it was towards the end of september, because i took advantage of the special maps offer.

Im sure they took the money then, because i remember at the time it was when fifa was released, i bought an xbox copy for a friend because he was away on holiday and a ps3 copy for myself. But my friend managed to get another copy from someone else, so i returned the one copy. When i was checking my statement, i was charged three times and i was thinking i should have only been charged twice, but then i realised one transaction was call of duty black ops, the other was fifa 13 on ps3, the other was the xbox fifa 13, but it hadnt shown up as refunded as i asked for the cash instead.

But now ive checked my online banking, and ive been charged for call of duty again. And my online banking doesnt go any further than 28 of september which is just after i made the transaction. obviously i have to wait until monday before i can properley check, but surely to pre order a game to have it sent to your house, especially with an exclusive special feature, u would have to pay in advance or some sort of deposit.

Has anyone else pre ordered call of duty black ops with the special map pack, and feel like they have been charged twice? Or does anyone know how preordering works with tesco.

It doesnt help that i ordered it via Tesco entertainment, and now the site is unavailable, and when i check on my normal tesco direct account, it doesnt come up as a transaction.

TIA