The telephone number +44 345 600 6006 is being used by scammers purporting to represent the Co-op bank. If you recieve a call from the number +44 345 600 6006, which may appear as 0345 600 6006, then you should delete and block the number.
The hallmark of scam calls such as the one from +44 345 600 6006 is that the caller attempts to extract personal and banking information from the recipient. In this case the callers suggest that they are phoning as representatives of the Co-operative bank. Of course they are looking to extract information from any potential recipient of their calls. You need to avoid giving them any chance to extract you information by cutting the call short. You can also report the call to the co-op bank team if you wish by emailing ihaveseenascam@co-operativebank.co.uk.