First, try removing any hair or soap or food debris that could be the cause of the blockage. If this doesn’t work try using a foaming sink unblocker, which you can buy from many DIY or hardware stores or supermarkets.
Make sure you get the foaming type as it coats the pipes and is more effective. Please make sure you follow the instructions carefully.
Please note that bleach will not clear a blocked pipe. However we recommend using bleach or foaming sink cleaner regularly (about once a month) to keep your pipes clean and free from debris.
It is your responsibility to ensure sinks and pipes are clean and clear. If an engineer attends and the blockage could have been cleared by you, it is likely you will be re-charged for this work.