Tiered interest rate

Several banks have offered tiered interest rate on savings accounts. A different interest rate is applied to different tranches of savings. This type of complicated structures bring two issues:
a) does the bank state clearly how the interest is to be computed?
b) is the customer able to check that the correct amount of interest has been credited?
In a savings account, the balance can fluctuate every day. Does the bank apply the tiered interest calculation on the daily balance?
Will the bank be willing to show each customer how the interest credited in each month is calcuated?
I hope that bank customers are given the correct amount of interest and are not short changed, due to their inability to check on the calculation of the interest.