Something acting strange on my credit card...?

Two days ago, some money was missing from my account, but without it being shown as a value on the list... When i asked a bank clerk, he told me that it was due to a buy i have done. The value of the money missing was same - alike the buy i had done, so i ignored it. But when i got some money posted into my account, the total value was the same as before, just as if the money wasnt added.. Im scared.... Should i be??????