Complex sentence: Customers' numbers are normally not the same as account numbers, because a number of customer acconumber can be linked to any account that the customer controls, such as cheque, savings, loan, credit card and other accounts.
Split into simpler sentences: Customers' numbers are normally not the same as account numbers, because a number of customer accounts can be linked to the one customer number. The customer number can be linked to any account that the customer controls, such as cheque, savings, loan, credit card and other accounts.