Transfers can take different amounts of time to be completed depending on the type of payment. For example, salaries (usually paid via BACs) can take up to 3 working days, but personal bank transfers are usually completed within 2 hours.
You also need to check if the sender has entered your bank details correctly. If all the details are correct and you still have not received the money, the sender needs to get in touch with their own bank. Unfortunately, we would not be able to see why the payment has not gone through.