To stop a cheque in Bankline you'll need the relevant account servicing privileges. 

Can you see and select ‘Account servicing’ in the top menu?

If yes, please follow these steps:

1. Select 'Account servicing’, which will open in a new tab.
2. Click ‘Stop cheque’.
3. Select the account that the cheque is from, then choose whether you want to cancel an individual cheques (up to 10), range of cheques or a bulk list of cheques (up to 500).
4. Fill in the required fields, then click ‘Submit to bank’.

If no, you’ll need to contact your customer service team.